📘 Computer Fundamentals and Programming with C

Module 1 : Overview of C (Part 1)

📚 Contents

✅ Introduction to Programming

✅ What is C?

✅ History of C

✅ Evolution of C

✅ Features of C

✅ Advantages of C

✅ Applications of C

🎯 Learning Objectives

After completing this lesson, students will be able to:

Understand the concept of programming.
Explain the importance of the C programming language.
Describe the history and evolution of C.
Identify the major features of C.
Explain the applications of C in real-world computing.

1. Introduction to Programming

What is Programming?

Programming is the process of creating a sequence of instructions that enables a computer to perform a specific task. These instructions are written using a programming language and are collectively called a program.

A computer cannot understand human language directly. Therefore, programmers write instructions in a programming language, which are later translated into machine language by a compiler or interpreter.

Programming is not just about writing code; it also involves analyzing problems, designing solutions, testing programs, and maintaining software.

Why Do We Need Programming?

Programming is essential because computers require precise instructions to perform tasks. Without programming, computers cannot process data, solve problems, or execute applications.

Programming is used to develop:

Operating Systems
Mobile Applications
Desktop Software
Websites
Games
Banking Software
Artificial Intelligence Applications
Embedded Systems

💡 Remember

A computer never guesses. It only performs the instructions provided by the programmer.

2. What is C Programming?

C is a general-purpose, procedural programming language designed to develop efficient and reliable software.

It provides the programmer with both high-level programming features and low-level memory access, making it suitable for developing operating systems as well as application software.

Because of its speed, simplicity, and flexibility, C is often referred to as the foundation of modern programming languages.

Definition

C is a procedural, compiled, and general-purpose programming language developed by Dennis Ritchie at Bell Laboratories in 1972 for developing the UNIX operating system.

📌 Characteristics of C

General-purpose language
Procedural programming language
Middle-level language
Compiled language
Portable
Efficient
Structured
Fast execution
Rich library support

3. History of C Programming

During the 1960s and early 1970s, computer programmers required a language that was efficient, portable, and capable of system-level programming. Existing languages either lacked flexibility or were too closely tied to specific hardware.

To address these limitations, Dennis Ritchie developed the C programming language at Bell Laboratories in 1972. It was initially created to rewrite significant portions of the UNIX operating system.

The language quickly gained popularity because it combined the efficiency of low-level languages with the readability of high-level languages. Over time, C became one of the most influential programming languages in the history of computing.

👨‍💻 Dennis Ritchie

Dennis MacAlistair Ritchie was an American computer scientist and one of the most influential pioneers in software development.

Major Contributions

Developed the C programming language.
Co-developed the UNIX operating system.
Influenced the design of many modern programming languages.
Received the ACM Turing Award in 1983 for his contributions to computer science.

🏢 Bell Laboratories

Bell Laboratories (Bell Labs) is a world-renowned research organization known for groundbreaking innovations in science and technology.

Notable inventions from Bell Labs include:

C Programming Language
UNIX Operating System
Transistor
Information Theory
UNIX Utilities

4. Evolution of C Programming

The C language evolved from earlier programming languages developed for system programming.

Language	Developer	Year	Purpose
ALGOL	International Committee	1960	Scientific Computing
BCPL	Martin Richards	1967	System Programming
B	Ken Thompson	1970	UNIX Development
C	Dennis Ritchie	1972	General & System Programming

Evolution Flow


ALGOL
   ↓
BCPL
   ↓
B Language
   ↓
C Language
   ↓
C++
   ↓
Java
   ↓
C#

5. Why Was C Developed?

The B programming language lacked several important features such as support for multiple data types and efficient system programming.

C was developed to overcome these limitations by providing:

Better performance
Efficient memory management
Support for different data types
Structured programming
Portability across systems

6. Features of C Programming

1. Simple

C has a straightforward syntax and a relatively small set of keywords, making it easier to learn.

2. Fast

Programs written in C execute quickly because they are compiled into machine code.

3. Portable

The same C program can often run on different operating systems with little or no modification.

4. Structured

C encourages dividing large programs into smaller functions, improving readability and maintenance.

5. Rich Library

The C Standard Library provides numerous built-in functions for input/output, mathematics, string handling, memory management, and file operations.

6. Middle-Level Language

C combines the advantages of high-level programming with the ability to perform low-level operations such as direct memory access.

7. Dynamic Memory Management

C allows memory to be allocated and released during program execution using functions like malloc(), calloc(), realloc(), and free().

7. Advantages of C

Easy to understand
Fast execution
Efficient use of memory
Portable across platforms
Supports modular programming
Extensive standard library
Widely used in industry
Ideal for learning programming fundamentals

8. Applications of C

C is used in many areas of computing, including:

Operating Systems (e.g., UNIX, Linux)
Embedded Systems
Device Drivers
Database Management Systems
Compiler Development
Network Programming
Scientific and Engineering Applications
Robotics
Internet of Things (IoT)
Game Development

📌 Key Points

C is a general-purpose programming language.
It was developed by Dennis Ritchie.
C was created at Bell Laboratories in 1972.
C was originally developed for the UNIX operating system.
C remains one of the most widely taught programming languages.

📝 Summary

This part introduced the fundamentals of programming and the C programming language. We explored why programming is important, learned about the origin and evolution of C, discussed its major features and advantages, and examined its wide range of applications. These concepts provide the foundation for understanding the rest of the course.

📘 Computer Fundamentals and Programming with C

Module 1 – Part 2

Basic Structure of a C Program

🎯 Learning Objectives

After studying this chapter, you will be able to:

Understand the structure of a C program.
Explain the purpose of each section of a C program.
Write and execute your first C program.
Understand the compilation and execution process.
Use comments correctly.

1. Introduction

Every programming language follows a specific structure or format. Similarly, a C program consists of several components that work together to perform a task.

A well-structured C program is easier to understand, debug, modify, and maintain. Although some parts of a C program are optional, the main() function is mandatory because program execution always begins from this function.

2. Basic Structure of a C Program

A simple C program contains the following sections:


Documentation Section
↓

Link Section

↓

Definition Section

↓

Global Declaration Section

↓

main() Function

↓

User-defined Functions

3. Components of a C Program

(a) Documentation Section

This section contains comments that describe the purpose of the program.

Example


/* Program to print Hello World */

Comments improve readability but are ignored by the compiler.

(b) Link Section

The link section includes the required header files.

Example


#include<stdio.h>

The #include directive tells the compiler to include the contents of the header file before compilation.

(c) Definition Section

This section defines symbolic constants using the #define directive.

Example


#define PI 3.14159

Here, every occurrence of PI is replaced with 3.14159 before compilation.

(d) Global Declaration Section

Variables and function prototypes declared outside all functions are called global declarations.

Example


int total;
float average;

These variables can be accessed by all functions in the program.

(e) main() Function

The main() function is the starting point of every C program.

General syntax:


int main()
{

    statements;

    return 0;

}

The statements inside the braces { } are executed sequentially.

(f) User-defined Functions

These are additional functions created by the programmer to perform specific tasks.

Example


void display()
{
    printf("Welcome");
}

Functions improve code reusability and modularity.

4. First C Program


#include<stdio.h>

int main()
{
    printf("Hello, World!");

    return 0;
}

Output


Hello, World!

5. Explanation of the Program

Line 1


#include<stdio.h>

Includes the Standard Input Output library.

Line 2


int main()

Declares the main function.

Line 3

Marks the beginning of the function body.

Line 4


printf("Hello, World!");

Displays the message on the screen.

Line 5


return 0;

Indicates successful completion of the program.

Line 6

Marks the end of the function.

6. Flow of Program Execution


Source Code
      │
      ▼
Compiler
      │
      ▼
Object Code
      │
      ▼
Linker
      │
      ▼
Executable File
      │
      ▼
Program Output

7. Compilation Process

The execution of a C program takes place in four stages:

Step 1: Preprocessing

Header files are included.
Macros are expanded.

Step 2: Compilation

Source code is converted into assembly language.

Step 3: Assembling

Assembly code is converted into object code.

Step 4: Linking

Library functions are linked.
Executable file is generated.

8. Header Files

A header file contains declarations of library functions.

Common header files are:

Header File	Purpose
stdio.h	Input and Output
math.h	Mathematical Functions
string.h	String Functions
stdlib.h	Memory Management
time.h	Date and Time

9. The printf() Function

The printf() function is used to display output.

Syntax


printf("message");

Example


printf("Programming in C");

Output


Programming in C

10. The return Statement

The return statement terminates the function and returns control to the operating system.

Example


return 0;

A return value of 0 generally indicates that the program executed successfully.

11. Comments in C

Comments are explanatory notes written within a program to improve readability. They are ignored by the compiler.

Single-line Comment


// This is a comment

Multi-line Comment


/*
This
is
a
comment
*/

12. Rules for Writing a C Program

Every program must contain the main() function.
Every statement should end with a semicolon (;).
Curly braces {} define the function body.
Keywords must be written correctly.
C is case-sensitive.
Header files should be included before using library functions.

13. Advantages of a Proper Program Structure

Easy to read
Easy to debug
Easy to maintain
Supports teamwork
Reduces errors
Improves program efficiency

📘 Computer Fundamentals and Programming with C

Module 1 – Part 3

Algorithms and Structured Programming

🎯 Learning Objectives

After studying this chapter, students will be able to:

Define an algorithm.
Explain the characteristics of a good algorithm.
Write algorithms for simple problems.
Understand the concept of structured programming.
Explain the three basic programming constructs.
Differentiate between an algorithm and a program.
Appreciate the importance of structured programming in software development.

1. What is an Algorithm?

An algorithm is a finite sequence of clear and logical steps designed to solve a specific problem or perform a particular task.

An algorithm is independent of any programming language. It focuses on the logic required to solve a problem rather than the syntax of a programming language.

Definition

An algorithm is a well-defined sequence of instructions that, when followed correctly, produces the desired output from the given input and terminates after a finite number of steps.

2. Why Do We Need an Algorithm?

Before writing a program, a programmer should first think about the solution. An algorithm provides a systematic approach for solving a problem.

Benefits

Makes problem solving easier.
Reduces programming errors.
Saves development time.
Improves program quality.
Makes debugging simpler.
Helps in planning program logic.

💡 Real-Life Example

Problem

Prepare a cup of tea.

Algorithm

Start
Take a saucepan.
Pour water into the saucepan.
Add tea leaves.
Add sugar.
Boil the mixture.
Add milk.
Boil again.
Filter the tea.
Serve.
Stop.

This example shows that an algorithm is simply a sequence of logical steps.

3. Characteristics of a Good Algorithm

A good algorithm should have the following characteristics.

(i) Input

An algorithm should accept zero or more inputs.

Example

Input:


Two numbers

(ii) Output

It should produce at least one output.

Example

Output:


Sum of two numbers

(iii) Definiteness

Every step should be precise and unambiguous.

Correct


Read two numbers.

Incorrect


Read some values.

(iv) Finiteness

An algorithm must terminate after a finite number of steps.

(v) Effectiveness

Each step should be simple and executable.

4. Advantages of Algorithms

Easy to understand.
Independent of programming language.
Helps in debugging.
Improves logical thinking.
Simplifies coding.
Makes documentation easier.

5. Limitations of Algorithms

Time-consuming for very large problems.
Difficult to represent complex logic in simple steps.
Cannot be executed directly by a computer.

6. Steps in Problem Solving


Problem
      │
      ▼
Analysis
      │
      ▼
Algorithm
      │
      ▼
Flowchart
      │
      ▼
Program
      │
      ▼
Testing
      │
      ▼
Output

7. Algorithm vs Program

Algorithm	Program
Sequence of logical steps	Written in a programming language
Easy to understand	Requires knowledge of syntax
Independent of language	Language dependent
Cannot be executed directly	Executable by a computer
Used for planning	Used for implementation

8. Algorithm Examples

Example 1

Problem

Find the sum of two numbers.

Algorithm

Start
Read A and B.
Calculate Sum = A + B.
Display Sum.
Stop.

Example 2

Problem

Find the largest of two numbers.

Algorithm

Start
Read A and B.
If A > B, display A.
Otherwise display B.
Stop.

Example 3

Problem

Calculate the area of a rectangle.

Algorithm

Start
Read Length and Breadth.
Area = Length × Breadth.
Display Area.
Stop.

9. Introduction to Structured Programming

As software became larger and more complex, programmers needed a disciplined approach to writing programs. This led to the development of structured programming.

Structured programming is a programming methodology that organizes a program into smaller, manageable units and avoids unnecessary jumps in execution.

Definition

Structured programming is a programming approach in which a program is developed using well-defined control structures such as sequence, selection, and iteration.

10. Objectives of Structured Programming

Improve readability.
Reduce complexity.
Simplify debugging.
Encourage modular design.
Improve maintainability.

11. Basic Programming Constructs

Structured programming is based on three fundamental control structures.

(i) Sequence

Statements are executed one after another in the order they appear.

Example


int a = 5;
int b = 10;
int sum = a + b;
printf("%d", sum);

(ii) Selection

Selection allows the program to choose one path from multiple alternatives based on a condition.

Examples

if
if-else
switch

Example


if (marks >= 40)
    printf("Pass");
else
    printf("Fail");

(iii) Iteration

Iteration repeats a block of statements until a condition becomes false.

Examples

while
do-while
for

Example


for(i = 1; i <= 5; i++)
{
    printf("%d", i);
}

12. Advantages of Structured Programming

Programs are easier to understand.
Reduces programming errors.
Simplifies testing.
Easier maintenance.
Encourages code reuse through functions.
Improves software quality.

13. Structured vs Unstructured Programming

Structured Programming	Unstructured Programming
Uses functions	Often uses excessive `goto` statements
Easy to read	Difficult to understand
Easier debugging	Debugging is difficult
Modular	Monolithic
Better maintenance	Poor maintenance

14. Applications of Structured Programming

Structured programming is widely used in:

Banking Software
Inventory Management Systems
School Management Systems
Hospital Information Systems
Payroll Systems
Scientific Applications
Database Applications

📌 Key Points

An algorithm is a sequence of logical steps for solving a problem.
Every algorithm should have input, output, finiteness, definiteness, and effectiveness.
Structured programming improves software quality by using clear control structures.
The three basic programming constructs are Sequence, Selection, and Iteration.

📚 Summary

Algorithms provide a clear plan before programming begins. They help programmers think logically and organize solutions step by step. Structured programming builds on this idea by dividing programs into manageable components and using three basic control structures—sequence, selection, and iteration. Together, algorithms and structured programming form the foundation of effective software development in C.

📘 Computer Fundamentals and Programming with C

Module 1 – Part 4

Character Set, Tokens, Keywords, Constants, Variables, Data Types and Storage Classes

🎯 Learning Objectives

After studying this chapter, students will be able to:

Explain the C character set.
Define tokens and identify different types of tokens.
Distinguish between keywords and identifiers.
Explain constants and variables with examples.
Describe different data types available in C.
Understand the purpose and types of storage classes.

1. Character Set in C

Introduction

Just as every spoken language has its own alphabet, the C programming language has a defined set of valid characters. These characters are used to write program statements, variable names, operators, and symbols. This collection of permitted characters is known as the character set.

A C compiler accepts only characters that belong to the C character set. Using invalid characters may lead to compilation errors.

Definition

A character set is the collection of letters, digits, symbols, and special characters that are recognized by the C compiler.

Categories of Character Set

(a) Alphabetic Characters

Uppercase letters


A B C ... Z

Lowercase letters


a b c ... z

(b) Numeric Digits


0 1 2 3 4 5 6 7 8 9

(c) Special Characters


+  -  *  /  %  =  <  >  !  &  |  ^  ~
( ) { } [ ] ; : , . # ? _ ' " \

(d) White Space Characters

These improve readability but generally do not affect program execution.

Space
Tab
New Line
Carriage Return

Importance

The character set forms the foundation of every C program. Variables, operators, keywords, and statements are all created using these characters.

2. Tokens

Introduction

A C program is made up of many small units such as keywords, identifiers, constants, operators, and punctuation symbols. These smallest meaningful units are called tokens.

Definition

A token is the smallest individual unit of a C program that carries meaning for the compiler.

Types of Tokens

Token	Example
Keywords	int, if
Identifiers	total, marks
Constants	10, 3.14
String Literals	"Hello"
Operators	+, -, *
Special Symbols	; , { } ( )

Example


int age = 20;

Tokens are:


int
age
=
20
;

3. Keywords

Introduction

Keywords are reserved words that have predefined meanings in the C language. Their purpose is fixed, and they cannot be used as names for variables, functions, or arrays.

Definition

A keyword is a reserved word in C that has a predefined meaning and cannot be redefined by the programmer.

Common Keywords

Keyword	Purpose
int	Integer data type
float	Floating-point data type
char	Character data type
if	Conditional statement
else	Alternative condition
for	Loop
while	Loop
return	Return control
break	Exit loop
continue	Skip current iteration

4. Identifiers

An identifier is a name given by the programmer to variables, functions, arrays, or other program elements.

Valid Identifiers


total
studentName
_marks
salary2025

Invalid Identifiers


2marks
student name
float

Rules for Naming Identifiers

Must begin with a letter or underscore.
Cannot start with a digit.
Cannot contain spaces.
Cannot be a keyword.
C is case-sensitive (Marks and marks are different).

5. Constants

Introduction

A constant is a fixed value whose value remains unchanged throughout program execution.

Types of Constants

Integer Constant


10
250
-35

Floating Constant


3.14
25.75
0.001

Character Constant


'A'
'Z'
'9'

String Constant


"Computer"
"C Programming"

Symbolic Constant


#define PI 3.14159

6. Variables

Introduction

A variable is a named memory location used to store data during program execution. Unlike constants, variables can change their values whenever required.

Declaration


int age;
float salary;
char grade;

Initialization


int age = 20;

Variable Naming Rules

✔ Begin with a letter or underscore.

✔ Cannot contain spaces.

✔ Cannot use keywords.

✔ May contain digits after the first character.

7. Data Types

Introduction

A data type specifies the type of value that a variable can store and the amount of memory allocated to it.

Basic Data Types

Data Type	Description	Example
int	Stores integers	int age;
char	Stores characters	char grade;
float	Stores decimal numbers	float price;
double	Stores large decimal values	double salary;
void	Represents no value	void display();

Derived Data Types

Arrays
Functions
Pointers

User-defined Data Types

Structure
Union
Enumeration
typedef

8. Storage Classes

Introduction

Storage classes determine where a variable is stored, how long it exists, and where it can be accessed.

Types of Storage Classes

(a) auto

Default storage class for local variables.


auto int x;

(b) register

Requests storage in CPU registers for faster access.


register int count;

(c) static

Retains its value between function calls.


static int total;

(d) extern

Used to access global variables declared in another file.


extern int marks;

Comparison of Storage Classes

Storage Class	Scope	Lifetime	Default Value
auto	Local	Function execution	Garbage value
register	Local	Function execution	Garbage value
static	Local/Global	Entire program	0
extern	Global	Entire program	0

📘 Computer Fundamentals and Programming with C

Module 2: Operators, Expressions and Preprocessor Directives

Duration: 8 Lectures

📚 Module Contents

Introduction to Operators
Types of Operators
Arithmetic Operators
Relational Operators
Logical Operators
Assignment Operators
Increment & Decrement Operators
Conditional (Ternary) Operator
Bitwise Operators
Special Operators
Operator Precedence and Associativity
Expressions
Type Conversion and Type Casting
Input and Output Functions
Comments in C
Preprocessor Directives
Macros

🎯 Learning Outcomes

After completing this module, students will be able to:

Explain different types of operators in C.
Evaluate arithmetic and logical expressions.
Understand operator precedence and associativity.
Use input/output functions effectively.
Apply type conversion and type casting.
Use preprocessor directives and macros.

1. Introduction to Operators

What is an Operator?

An operator is a special symbol used to perform operations on one or more operands (variables or constants). Operators allow programmers to perform calculations, compare values, assign data, and manipulate bits.

Definition

An operator is a symbol that instructs the compiler to perform a specific mathematical, logical, relational, or bitwise operation on one or more operands.

Example


int a = 10, b = 5;
int sum = a + b;

Here,

a and b are operands.
+ is the operator.

Output:


sum = 15

2. Classification of Operators

C provides several categories of operators.

Operator Type	Purpose	Example
Arithmetic	Mathematical calculations	+ - * / %
Relational	Compare values	> < >= <= == !=
Logical	Combine conditions	&& \|\| !
Assignment	Assign values	= += -= *=
Increment/Decrement	Increase or decrease value	++ --
Conditional	Decision making	?:
Bitwise	Operate on binary bits	& \| ^ ~ << >>
Special	Special operations	sizeof, comma, pointer

3. Arithmetic Operators

Arithmetic operators perform mathematical calculations.

Operator	Meaning	Example
+	Addition	a+b
-	Subtraction	a-b
*	Multiplication	a*b
/	Division	a/b
%	Modulus	a%b

Example


#include<stdio.h>

int main()
{
    int a=20,b=6;

    printf("Addition = %d\n",a+b);
    printf("Subtraction = %d\n",a-b);
    printf("Multiplication = %d\n",a*b);
    printf("Division = %d\n",a/b);
    printf("Remainder = %d",a%b);

    return 0;
}

Output


Addition = 26
Subtraction = 14
Multiplication = 120
Division = 3
Remainder = 2

4. Relational Operators

Relational operators compare two values and return either 1 (true) or 0 (false).

Operator	Meaning
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal
==	Equal to
!=	Not equal to

Example


int a=10,b=20;

printf("%d",a<b);

Output

5. Logical Operators

Logical operators are used to combine multiple conditions.

Operator	Meaning
&&	Logical AND
\|\|	Logical OR
!	Logical NOT

Example


int age=20;

if(age>=18 && age<=60)
    printf("Eligible");

Output


Eligible

6. Assignment Operators

Assignment operators assign values to variables.

Operator	Meaning
=	Assignment
+=	Add and assign
-=	Subtract and assign
*=	Multiply and assign
/=	Divide and assign
%=	Modulus and assign

Example


int x=10;

x+=5;

Result


x=15

7. Increment and Decrement Operators

These operators change the value of a variable by one.

Increment (++)


int x=5;

x++;

Output

Decrement (--)


int x=5;

x--;

Output

Prefix vs Postfix

Prefix	Postfix
++x	x++
Value changes first	Value changes later

8. Conditional (Ternary) Operator

The conditional operator is a compact alternative to the if-else statement.

Syntax


condition ? expression1 : expression2;

Example


int a=20,b=10;

int max=(a>b)?a:b;

printf("%d",max);

Output

9. Bitwise Operators

Bitwise operators perform operations directly on binary bits.

Operator	Meaning
&	Bitwise AND
\|	Bitwise OR
^	XOR
~	NOT
<<	Left Shift
>>	Right Shift

Example


int a=5,b=3;

printf("%d",a&b);

Output

10. Special Operators

Common special operators include:

Operator	Purpose
sizeof	Finds memory size
,	Comma operator
&	Address operator
*	Pointer operator

Example


printf("%d",sizeof(int));

Output (may vary by system)

11. Operator Precedence

When multiple operators appear in an expression, C follows precedence rules.

Example


10+5*2

Multiplication is performed first.

Result

12. Associativity

Associativity determines the evaluation order when operators have the same precedence.

Example


20-10-5

Evaluated as


(20-10)-5 = 5

because subtraction is left to right.

📌 Key Points

Operators perform operations on operands.
Arithmetic operators are used for calculations.
Relational operators compare values.
Logical operators combine conditions.
Assignment operators store values.
Increment and decrement operators modify values by one.
The conditional operator is a shorthand for simple if-else statements.
Bitwise operators work on binary representations of numbers.
Precedence and associativity determine the order of evaluation.

📝 Summary

Operators are essential elements of the C language that allow programmers to perform calculations, compare values, evaluate conditions, manipulate bits, and assign data. Understanding the different categories of operators, along with operator precedence and associativity, helps in writing accurate and efficient C programs.

📘 Computer Fundamentals and Programming with C

Module 2 – Part 2

Expressions, Type Conversion, Input/Output, Preprocessor Directives and Macros

📚 Contents

Expressions in C
Types of Expressions
Type Conversion
Type Casting
Input Functions
Output Functions
Escape Sequences
Comments
Preprocessor Directives
Macros

🎯 Learning Outcomes

After studying this chapter, students will be able to:

Understand expressions and their evaluation.
Explain automatic type conversion.
Perform explicit type casting.
Use input and output functions correctly.
Apply escape sequences in output.
Explain preprocessor directives and macros.

1. Expressions in C

Introduction

An expression is a combination of operands (constants, variables, or function calls) and operators that evaluates to a single value.

Expressions are the foundation of computations in C. They are used in assignments, conditions, loops, and function calls.

Definition

An expression is a valid combination of variables, constants, operators, and function calls that produces a single value when evaluated.

Example


int a = 10;
int b = 20;

int c = a + b;

Here,


a + b

is an expression.

Result

Types of Expressions

(a) Arithmetic Expression

Performs mathematical calculations.

Example


x + y


a * b

(b) Relational Expression

Compares two values.

Example


a > b

Result


True or False

(c) Logical Expression

Uses logical operators.

Example


(a>b)&&(b>c)

(d) Assignment Expression

Assigns value.

Example


x = 10

(e) Conditional Expression

Uses the ternary operator.

Example


(a>b)?a:b

2. Type Conversion

Introduction

Sometimes an expression contains different data types. The compiler automatically converts smaller data types into larger compatible data types.

This process is called Type Conversion.

It is also known as Implicit Type Conversion.

Example


int a=10;

float b=5.5;

float c=a+b;

The integer value is automatically converted into float.

Output


15.5

Rules of Automatic Type Conversion


char
↓

int
↓

float
↓

double

Smaller data types are promoted to larger data types automatically.

Advantages

Prevents data loss.
Makes calculations easier.
Performed automatically by the compiler.

3. Type Casting

Introduction

Sometimes the programmer wants to convert a value into another data type manually.

This is called Type Casting.

Syntax


(data_type) expression;

Example


int a=10,b=3;

float c=(float)a/b;

printf("%f",c);

Output


3.333333

Without casting, the result would be

because integer division truncates the decimal part.

Type Conversion vs Type Casting

Type Conversion	Type Casting
Automatic	Manual
Compiler performs conversion	Programmer performs conversion
No syntax required	Uses `(data_type)`
Safe conversion	Depends on programmer

4. Input Functions

scanf()

The scanf() function reads data from the keyboard.

Syntax


scanf("format",&variable);

Example


#include<stdio.h>

int main()
{
    int age;

    printf("Enter Age : ");

    scanf("%d",&age);

    printf("Age = %d",age);

    return 0;
}

Output


Enter Age : 20

Age = 20

Common Format Specifiers

Data Type	Format Specifier
int	%d
float	%f
char	%c
double	%lf
string	%s

5. Output Functions

printf()

The printf() function displays information on the screen.

Syntax


printf("format",variable);

Example


int marks=90;

printf("Marks=%d",marks);

Output


Marks=90

Advantages

Displays formatted output.
Supports multiple variables.
Supports escape sequences.

6. Escape Sequences

Escape sequences begin with a backslash (\) and represent special characters.

Escape Sequence	Meaning
\n	New Line
\t	Horizontal Tab
\b	Backspace
\r	Carriage Return
\	Backslash
"	Double Quote
'	Single Quote

Example


printf("Hello\nWorld");

Output


Hello
World

Example


printf("A\tB\tC");

Output


A      B      C

7. Comments

Comments improve readability by explaining program logic. They are ignored by the compiler.

Single Line Comment


// This is a comment

Multi-line Comment


/*
This is
a comment
*/

Advantages

Makes programs easier to understand.
Helps during debugging.
Improves documentation.

8. Preprocessor Directives

Introduction

Preprocessor directives are instructions processed before compilation.

They always begin with the # symbol.

Common Directives

Directive	Purpose
#include	Includes header file
#define	Defines constant
#ifdef	Conditional compilation
#ifndef	Conditional compilation
#undef	Removes macro

Example


#include<stdio.h>

Includes the Standard Input Output library.

Example


#define PI 3.14159

Defines a symbolic constant.

Advantages

Reduces repeated code.
Improves readability.
Simplifies maintenance.

9. Macros

Introduction

A macro is a named fragment of code created using the #define directive. During preprocessing, every occurrence of the macro name is replaced by its definition.

Macros improve readability and reduce duplication.

Syntax


#define name replacement

Example


#define PI 3.14159

float area = PI * r * r;

Function-like Macro


#define SQUARE(x) ((x)*(x))

Usage


printf("%d",SQUARE(5));

Output

Advantages of Macros

Faster execution.
No function call overhead.
Easy modification.
Improves readability.

📌 Key Points

Expressions evaluate to a single value.
Type conversion is automatic.
Type casting is performed manually.
scanf() is used for input.
printf() is used for output.
Escape sequences control text formatting.
Comments improve readability.
Preprocessor directives are executed before compilation.
Macros simplify repetitive tasks.

📚 Module 2 Summary

Module 2 introduced operators, expressions, input/output functions, type conversion, type casting, comments, preprocessor directives, and macros. These concepts enable programmers to write efficient, readable, and maintainable C programs. Understanding these topics is essential before learning decision-making statements and loops in the next module.

📘 Computer Fundamentals and Programming with C

Module 3: Decision Making and Loop Control

Duration: 7 Lectures

📚 Module Contents

Decision Making in C
Simple if Statement
if-else Statement
Nested if
else-if Ladder
switch Statement
Conditional (Ternary) Operator
while Loop
do-while Loop
for Loop
Nested Loops
break Statement
continue Statement
goto Statement
Solved Programs
University Questions
MCQs

🎯 Learning Outcomes

After completing this module, students will be able to:

Make decisions in C programs using conditional statements.
Select appropriate looping statements.
Develop efficient iterative solutions.
Differentiate between various looping constructs.
Control the flow of execution using jump statements.

1. Introduction to Decision Making

In everyday life, we make decisions based on certain conditions. For example, if it is raining, we carry an umbrella; otherwise, we do not. Similarly, in programming, a program often needs to choose between different actions depending on whether a condition is true or false.

Decision-making statements allow a program to execute specific instructions only when certain conditions are satisfied. These statements improve the flexibility and intelligence of programs.

2. The `if` Statement

Definition

The if statement executes a block of code only if the specified condition is true.

Syntax


if(condition)
{
    // Statements
}

Flowchart


        ┌────────────┐
        │ Condition? │
        └─────┬──────┘
              │
      True ───┘
              │
              ▼
      Execute Statements
              │
              ▼
             End

Example


#include<stdio.h>

int main()
{
    int marks = 80;

    if(marks >= 40)
    {
        printf("Pass");
    }

    return 0;
}

Output


Pass

3. The `if-else` Statement

When there are two possible outcomes, the if-else statement is used.

Syntax


if(condition)
{
    // True block
}
else
{
    // False block
}

Example


#include<stdio.h>

int main()
{
    int age = 16;

    if(age >= 18)
        printf("Eligible to Vote");
    else
        printf("Not Eligible");

    return 0;
}

Output


Not Eligible

4. Nested `if` Statement

A nested if means placing one if statement inside another.

Example


#include<stdio.h>

int main()
{
    int age = 22;
    char citizen = 'Y';

    if(age >= 18)
    {
        if(citizen == 'Y')
            printf("Eligible to Vote");
    }

    return 0;
}

5. `else-if` Ladder

The else-if ladder is used when multiple conditions need to be tested one after another.

Syntax


if(condition1)
{
}
else if(condition2)
{
}
else if(condition3)
{
}
else
{
}

Example: Grade Calculator


#include<stdio.h>

int main()
{
    int marks = 82;

    if(marks >= 90)
        printf("Grade A+");

    else if(marks >= 80)
        printf("Grade A");

    else if(marks >= 70)
        printf("Grade B");

    else if(marks >= 40)
        printf("Grade C");

    else
        printf("Fail");

    return 0;
}

Output


Grade A

6. `switch` Statement

The switch statement is used when one variable needs to be compared against multiple fixed values.

Syntax


switch(expression)
{
    case value1:
        statements;
        break;

    case value2:
        statements;
        break;

    default:
        statements;
}

Example


#include<stdio.h>

int main()
{
    int day = 3;

    switch(day)
    {
        case 1:
            printf("Monday");
            break;

        case 2:
            printf("Tuesday");
            break;

        case 3:
            printf("Wednesday");
            break;

        default:
            printf("Invalid Day");
    }

    return 0;
}

Output


Wednesday

7. Difference Between `if-else` and `switch`

`if-else`	`switch`
Can test ranges and complex conditions	Tests only fixed constant values
Suitable for relational and logical operators	Suitable for equality comparisons
Slower for many alternatives	Often easier to read for menu-driven programs

💡 Remember

Use if-else when conditions involve comparisons like >, <, >=, or logical operators.
Use switch when checking a variable against a list of constant values.

📌 Key Points

if executes a block only when a condition is true.
if-else chooses between two alternatives.
Nested if allows one decision inside another.
else-if ladder handles multiple conditions.
switch is useful for menu-driven programs.

📚 Summary

Decision-making statements enable a C program to choose different paths based on conditions. The if, if-else, nested if, else-if ladder, and switch statement are commonly used to implement selection logic. Choosing the appropriate statement improves program readability and efficiency.

📘 Computer Fundamentals and Programming with C

Module 3 – Part 2

Loop Control Statements in C

Duration: 7 Lectures

📚 Contents

Introduction to Loops
while Loop
do-while Loop
for Loop
Nested Loops
break Statement
continue Statement
goto Statement
Comparison of Loops
Solved Examples

🎯 Learning Outcomes

After completing this chapter, students will be able to:

Explain the need for loops.
Write programs using while, do-while, and for loops.
Understand nested loops.
Use break, continue, and goto statements effectively.
Compare different loop structures.

1. Introduction to Loop Control

In many programming situations, a group of statements needs to be executed repeatedly. Instead of writing the same statements multiple times, programmers use loops.

A loop executes a block of code repeatedly until a specified condition becomes false.

Real-Life Example

Imagine a teacher asks you to write your name 100 times. Writing it manually would be repetitive and time-consuming. A loop allows the computer to repeat the task automatically.

Definition

A loop is a control structure that repeatedly executes a block of statements as long as a specified condition is true.

Advantages of Loops

Reduces code repetition.
Saves programming time.
Improves readability.
Simplifies maintenance.
Reduces program size.

Types of Loops in C

There are three loop statements in C.

Loop	Condition Checked	Minimum Execution
while	Before execution	0 times
do-while	After execution	1 time
for	Before execution	0 times

2. while Loop

Definition

The while loop executes a block of statements repeatedly as long as the given condition remains true.

Syntax


while(condition)
{
    statements;
}

Flowchart


        ┌────────────┐
        │ Condition? │
        └─────┬──────┘
              │True
              ▼
        Execute Block
              │
              └───────────┐
                          │
                   False  ▼
                        End

Example 1

Display numbers from 1 to 5.


#include<stdio.h>

int main()
{
    int i=1;

    while(i<=5)
    {
        printf("%d ",i);
        i++;
    }

    return 0;
}

Output


1 2 3 4 5

Working

i	Condition	Output
1	True	1
2	True	2
3	True	3
4	True	4
5	True	5
6	False	Stop

Advantages

✔ Simple

✔ Suitable when the number of repetitions is unknown.

✔ Easy to understand.

Limitations

❌ Initialization must be done separately.

❌ Increment or decrement must be written manually.

3. do-while Loop

Definition

The do-while loop executes the statements first and checks the condition afterward.

Therefore, the loop executes at least once, even if the condition is initially false.

Syntax


do
{
    statements;

}while(condition);

Flowchart


      Execute Block
            │
            ▼
      Condition?
       │     │
     True   False
       │      │
       └──────┘
          End

Example


#include<stdio.h>

int main()
{
    int i=1;

    do
    {
        printf("%d ",i);
        i++;

    }while(i<=5);

    return 0;
}

Output


1 2 3 4 5

Important Difference


int i=10;

do
{
   printf("%d",i);

}while(i<5);

Output

Although the condition is false, the statement executes once.

4. for Loop

Definition

The for loop is mainly used when the number of repetitions is known in advance.

Syntax


for(initialization;condition;increment)
{
    statements;
}

Flowchart


Initialization
      │
      ▼
 Condition?
   │   │
 True False
  │      │
  ▼      End
Execute Block
      │
Increment
      │
──────┘

Example


#include<stdio.h>

int main()
{
    int i;

    for(i=1;i<=5;i++)
    {
        printf("%d ",i);
    }

    return 0;
}

Output


1 2 3 4 5

Advantages

✔ Compact

✔ Easy to write

✔ Suitable for counting loops

✔ Initialization, condition and update remain together.

5. Comparison of Loops

Feature	while	do-while	for
Condition Check	Before	After	Before
Executes Minimum	0	1	0
Initialization	Outside	Outside	Inside
Increment	Separate	Separate	Inside
Best Used	Unknown iterations	Menu-driven programs	Fixed iterations

6. Nested Loop

A loop inside another loop is called a nested loop.

Example


#include<stdio.h>

int main()
{
    int i,j;

    for(i=1;i<=3;i++)
    {
        for(j=1;j<=3;j++)
        {
            printf("* ");
        }

        printf("\n");
    }

    return 0;
}

Output


* * *
* * *
* * *

7. break Statement

The break statement immediately terminates the nearest loop or switch statement.

Example


#include<stdio.h>

int main()
{
    int i;

    for(i=1;i<=10;i++)
    {
        if(i==6)
            break;

        printf("%d ",i);
    }

    return 0;
}

Output


1 2 3 4 5

8. continue Statement

The continue statement skips the remaining statements in the current iteration and moves to the next iteration.

Example


#include<stdio.h>

int main()
{
    int i;

    for(i=1;i<=5;i++)
    {
        if(i==3)
            continue;

        printf("%d ",i);
    }

    return 0;
}

Output


1 2 4 5

9. goto Statement

The goto statement transfers program control directly to a labeled statement.

Syntax


goto label;

/* statements */

label:
statement;

Example


#include<stdio.h>

int main()
{
    printf("Welcome\n");

    goto end;

    printf("This line will not execute.\n");

end:
    printf("Program End");

    return 0;
}

Output


Welcome
Program End

Advantages of goto

Useful in rare situations such as exiting deeply nested loops.
Can simplify cleanup code in some low-level programs.

Disadvantages of goto

Makes programs difficult to understand.
Reduces readability.
Makes debugging difficult.
Should generally be avoided in structured programming.

📘 Computer Fundamentals and Programming with C

Module 4: Functions and Arrays

Theory: 10 Lectures

(Prepared for WBSU BCA Semester-I NEP Students)

🎯 Learning Outcomes

After completing this module, students will be able to:

Understand the concept and importance of functions in C.
Differentiate between library functions and user-defined functions.
Declare, define, and call functions.
Explain parameter passing techniques.
Understand recursion and recursive functions.
Create and manipulate one-dimensional and two-dimensional arrays.
Work with character arrays (strings) and string handling functions.

📚 Module Contents

Unit-1: Functions

Introduction to Functions
Advantages of Functions
Types of Functions
Function Declaration
Function Definition
Function Call
Function Prototype
Categories of Functions
Call by Value
Call by Reference
Recursive Functions

Unit-2: Arrays

Introduction to Arrays
One-Dimensional Array
Two-Dimensional Array
Multidimensional Arrays
Character Arrays (Strings)
String Handling Functions

PART-1

FUNCTIONS

1. Introduction to Functions

What is a Function?

A function is a self-contained block of code designed to perform a specific task. Instead of writing the same code repeatedly, we write it once inside a function and call it whenever needed.

Functions make programs modular, organized, and easier to maintain.

Definition

A function is a named block of statements that performs a specific operation and can be called whenever required during program execution.

Real-Life Analogy

Think of a calculator.

Each button performs a specific task.

Addition button → Add numbers
Subtraction button → Subtract numbers
Multiplication button → Multiply numbers

Similarly, every function performs one specific task.

Why Do We Need Functions?

Suppose you need to calculate the area of a circle 20 times.

Without functions, you would write the same code 20 times.

With functions, you simply write:


area();

whenever required.

Advantages of Functions

✅ Reduces program size

✅ Avoids code duplication

✅ Improves readability

✅ Easier debugging

✅ Easy maintenance

✅ Code reusability

✅ Supports teamwork

Structure of a Function

Every function consists of three parts.


Function Declaration
↓

Function Definition
↓

Function Call

Example


#include<stdio.h>

void display();

int main()
{
    display();

    return 0;
}

void display()
{
    printf("Welcome to C Programming");
}

Output


Welcome to C Programming

Components of the Above Program

Function Declaration


void display();

Tells the compiler that a function named display() exists.

Function Call


display();

Transfers program control to the function.

Function Definition


void display()
{
    printf("Welcome to C Programming");
}

Contains the actual statements.

Types of Functions

There are two types of functions.

1. Library Functions

These are predefined functions provided by C libraries.

Examples

Function	Purpose
printf()	Display output
scanf()	Read input
strlen()	Find string length
sqrt()	Square root
pow()	Power calculation
strcpy()	Copy string
strcat()	Concatenate strings

2. User-defined Functions

Functions created by the programmer are called user-defined functions.

Example


void welcome()
{
    printf("Welcome Students");
}

Function Prototype

A function prototype informs the compiler about

Function name
Return type
Parameters

Example


int sum(int,int);

Function Definition

General Syntax


return_type function_name(parameters)
{

    statements;

    return value;

}

Example


int add(int a,int b)
{
    return a+b;
}

Function Call

A function call transfers control to the function.

Example


result=add(10,20);

Categories of Functions

Functions are classified into four categories.

Category 1

No Arguments and No Return Value


void display()
{
    printf("Hello");
}

Call


display();

Category 2

Arguments but No Return Value


void sum(int a,int b)
{
    printf("%d",a+b);
}

Call


sum(10,20);

Category 3

No Arguments but Return Value


int number()
{
    return 50;
}

Call


x=number();

Category 4

Arguments and Return Value


int sum(int a,int b)
{
    return a+b;
}

Call


result=sum(10,20);

Call by Value

Definition

In Call by Value, a copy of the actual argument is passed to the function.

Any changes made inside the function do not affect the original variable.

Example


void change(int x)
{
    x=100;
}

Main


int a=10;

change(a);

printf("%d",a);

Output

Advantages

✔ Safe

✔ Original data remains unchanged

Disadvantages

✖ Extra memory is required

✖ Large data copying reduces efficiency

Call by Reference

Definition

In Call by Reference, the address of the variable is passed.

The function works on the original variable.

Changes made inside the function are reflected in the calling function.

Example


void change(int *x)
{
    *x=100;
}

Main


int a=10;

change(&a);

printf("%d",a);

Output

Difference Between Call by Value and Call by Reference

Call by Value	Call by Reference
Copy is passed	Address is passed
Original value unchanged	Original value changes
Uses normal variables	Uses pointers
More memory	Less memory

Recursive Function

Introduction

A function that calls itself is called a recursive function.

Example


void display()
{
    printf("Hello");

    display();
}

Types of Recursion

Direct Recursion

A function calls itself directly.


A()

↓

A()

Indirect Recursion

Two or more functions call each other.


A()

↓

B()

↓

A()

Advantages of Recursion

✔ Simple code

✔ Elegant solution

✔ Useful for trees and graphs

✔ Useful for divide-and-conquer algorithms

Disadvantages

✖ High memory usage

✖ Slower execution

✖ Risk of stack overflow

Applications of Recursion

Factorial
Fibonacci Series
Tower of Hanoi
Binary Search
Tree Traversal
Quick Sort
Merge Sort

📘 Computer Fundamentals and Programming with C

Module 4 – Part 2

Arrays and Strings in C

Theory: 10 Lectures

🎯 Learning Outcomes

After completing this chapter, students will be able to:

Understand the concept of arrays.
Declare and initialize one-dimensional and two-dimensional arrays.
Perform operations on arrays.
Work with character arrays (strings).
Use built-in string handling functions.
Develop simple programs using arrays and strings.

1. Introduction to Arrays

What is an Array?

An array is a collection of elements of the same data type stored in contiguous memory locations. Each element is identified by an index (subscript).

Instead of creating many separate variables, an array allows multiple values to be stored under a single name.

Definition

An array is a collection of similar data items stored in consecutive memory locations and accessed using a common name with an index number.

Why Do We Need Arrays?

Suppose you want to store the marks of 100 students.

Without arrays:


int m1,m2,m3,m4,...,m100;

With an array:


int marks[100];

Arrays make programs shorter, more organized, and easier to maintain.

Advantages of Arrays

✔ Store multiple values using one variable.

✔ Easy data processing.

✔ Faster access through indexing.

✔ Simplifies searching and sorting.

✔ Reduces code repetition.

Limitations of Arrays

❌ Can store only one data type.

❌ Fixed size after declaration.

❌ Insertion and deletion are relatively expensive.

Memory Representation


marks[5]

+-----+-----+-----+-----+-----+
| 80  | 75  | 90  | 85  | 95  |
+-----+-----+-----+-----+-----+
   0     1     2     3     4

The first element always has index 0.

2. One-Dimensional Array (1D Array)

A one-dimensional array stores elements in a single row.

Declaration


data_type array_name[size];

Example


int marks[5];

Initialization


int marks[5]={80,75,90,85,95};


int marks[]={80,75,90,85,95};

Accessing Array Elements


printf("%d",marks[2]);

Output

Program: Display Array Elements


#include<stdio.h>

int main()
{
    int a[5]={10,20,30,40,50};
    int i;

    for(i=0;i<5;i++)
    {
        printf("%d ",a[i]);
    }

    return 0;
}

Output


10 20 30 40 50

3. Reading Values into an Array


#include<stdio.h>

int main()
{
    int a[5],i;

    printf("Enter 5 numbers:\n");

    for(i=0;i<5;i++)
    {
        scanf("%d",&a[i]);
    }

    printf("\nArray Elements:\n");

    for(i=0;i<5;i++)
    {
        printf("%d ",a[i]);
    }

    return 0;
}

Applications of 1D Arrays

Store student marks
Employee salaries
Monthly sales
Temperatures
Exam scores

4. Two-Dimensional Array (2D Array)

A two-dimensional array stores data in rows and columns, similar to a table or matrix.

Declaration


data_type array_name[row][column];

Example


int marks[3][4];

Initialization


int a[2][3]={
{1,2,3},
{4,5,6}
};

Memory Representation


      Column

       0    1    2

Row0  10   20   30

Row1  40   50   60

Program


#include<stdio.h>

int main()
{
    int a[2][2]={{10,20},{30,40}};
    int i,j;

    for(i=0;i<2;i++)
    {
        for(j=0;j<2;j++)
        {
            printf("%d ",a[i][j]);
        }

        printf("\n");
    }

    return 0;
}

Output


10 20
30 40

Applications of 2D Arrays

Matrix operations
Student result tables
Chess board representation
Image processing
Game development

5. Multidimensional Arrays

Arrays having more than two dimensions are called multidimensional arrays.

Example


int data[2][3][4];

These are useful in scientific computing, simulations, graphics, and 3D applications.

6. Character Arrays (Strings)

A string is a sequence of characters terminated by the null character ('\0').

Example


char name[20];

Initialization


char name[]="Computer";

Memory Representation


C o m p u t e r \0

Reading a String


char name[20];

scanf("%s",name);

Displaying a String


printf("%s",name);

Program


#include<stdio.h>

int main()
{
    char name[30];

    printf("Enter Name : ");

    scanf("%s",name);

    printf("Welcome %s",name);

    return 0;
}

Output


Enter Name : Rahul

Welcome Rahul

7. String Handling Functions

The string.h header file provides several built-in functions for string manipulation.

(a) strlen()

Finds the length of a string.

Example


#include<stdio.h>
#include<string.h>

int main()
{
    char name[]="Computer";

    printf("%d",strlen(name));

    return 0;
}

Output

(b) strcpy()

Copies one string to another.

Example


char s1[]="ABC";
char s2[20];

strcpy(s2,s1);

(c) strcat()

Concatenates two strings.

Example


char s1[]="Good";
char s2[]="Morning";

strcat(s1,s2);

Output


GoodMorning

(d) strcmp()

Compares two strings.

Example


strcmp("ABC","ABC");

Output

A return value of:

0 → Strings are equal.
Positive value → First string is greater.
Negative value → Second string is greater.

(e) strrev()

Reverses a string (available in some compilers, not part of the ISO C standard).

Example


strrev(name);

(f) strlwr()

Converts a string to lowercase (compiler-specific).

(g) strupr()

Converts a string to uppercase (compiler-specific).

Commonly Used String Functions

Function	Purpose
`strlen()`	Finds string length
`strcpy()`	Copies a string
`strcat()`	Joins two strings
`strcmp()`	Compares two strings
`strrev()`	Reverses a string*
`strupr()`	Converts to uppercase*
`strlwr()`	Converts to lowercase*

Note: Functions marked with * are compiler-specific and are not included in the ISO C standard.

Difference Between Character Array and String

Character Array	String
Stores individual characters	Stores a sequence of characters
May not end with `'\0'`	Always ends with `'\0'`
Can represent any character data	Represents text

Advantages of Arrays

Easy storage of large amounts of data.
Fast element access using indices.
Simplifies algorithms such as sorting and searching.
Reduces the number of variables required.

Disadvantages of Arrays

Fixed size.
Cannot store different data types together.
Memory may be wasted if the declared size is larger than required.

📌 Key Points

Arrays store elements of the same data type.
Indexing starts from 0.
A 1D array stores data in a single list.
A 2D array stores data in rows and columns.
Strings are character arrays ending with a null character.
The <string.h> library provides functions for string manipulation.

📚 Module 4 Summary

This module introduced functions and arrays, two fundamental concepts in C programming. Functions help organize code into reusable units, while arrays enable efficient storage and processing of multiple values. The module also covered strings as character arrays and the use of standard string handling functions from the string.h library.

📘 Computer Fundamentals and Programming with C

Module 5: Pointers, Structures, Unions, File Handling and Dynamic Memory Allocation

(Theory: 15 Lectures)

(Prepared in original language for WBSU BCA NEP Semester-I Students)

🎯 Learning Outcomes

After completing this module, students will be able to:

Understand pointers and their applications.
Perform pointer arithmetic.
Pass pointers to functions.
Create and use structures and unions.
Perform dynamic memory allocation.
Read and write files using C.
Develop modular and memory-efficient programs.

📚 Module Contents

Unit 1: Pointers

Introduction to Pointers
Pointer Declaration
Pointer Initialization
Pointer Arithmetic
Pointer and Arrays
Pointer to Function
Passing Pointer to Function

Unit 2: Structures & Unions

Structure
Nested Structure
Array of Structures
Union
Difference between Structure and Union

Unit 3: Dynamic Memory Allocation

malloc()
calloc()
realloc()
free()

Unit 4: File Handling

File Concepts
fopen()
fclose()
fprintf()
fscanf()
fgets()
fputs()
EOF

PART-1

POINTERS

1. Introduction to Pointers

What is a Pointer?

A pointer is one of the most powerful features of the C programming language. A pointer is a variable that stores the memory address of another variable instead of storing the actual value.

Pointers allow programmers to access and manipulate memory directly, making programs more efficient and flexible.

Definition

A pointer is a variable that stores the memory address of another variable.

Why Do We Need Pointers?

Pointers are useful because they:

Access memory directly.
Reduce memory usage.
Pass arguments efficiently to functions.
Support dynamic memory allocation.
Build advanced data structures such as linked lists, stacks, queues, trees, and graphs.

Memory Representation


Variable        Address

a = 10          2000

Pointer p       3000
                │
                ▼
             Address 2000

Here,

Variable a stores 10.
Pointer p stores the address of a.

Pointer Declaration

Syntax


data_type *pointer_name;

Examples


int *p;

float *q;

char *ch;

Pointer Initialization


int a=10;

int *p;

p=&a;

Here

&a

means address of variable a.

Example Program


#include<stdio.h>

int main()
{
    int a=10;

    int *p;

    p=&a;

    printf("Value = %d\n",a);

    printf("Address = %p\n",&a);

    printf("Pointer = %p\n",p);

    return 0;
}

Output


Value = 10

Address = 6422296

Pointer = 6422296

(Address varies from computer to computer.)

Dereferencing Operator

The symbol * is called the dereferencing operator.

It retrieves the value stored at the memory location pointed to by the pointer.

Example


int a=50;

int *p=&a;

printf("%d",*p);

Output

Address Operator

The symbol & is called the address operator.

Example


printf("%p",&a);

Output


Address of a

Pointer Example


#include<stdio.h>

int main()
{
    int x=100;

    int *ptr=&x;

    printf("%d\n",x);

    printf("%d\n",*ptr);

    return 0;
}

Output


100

100

Pointer Arithmetic

Pointers can perform arithmetic operations.

Allowed operations are:

Increment (++)
Decrement (--)
Addition (+)
Subtraction (-)

Example


int a[5]={10,20,30,40,50};

int *p=a;

p++;

Now pointer points to

Memory Representation

Each integer occupies 4 bytes (commonly on modern systems).

Pointer and Array

The name of an array itself acts as a pointer to its first element.

Example


int a[5]={10,20,30,40,50};

printf("%d",*a);

Output

Example


printf("%d",*(a+2));

Output

Passing Pointer to Function

Example


#include<stdio.h>

void change(int *x)
{
    *x=100;
}

int main()
{
    int a=10;

    change(&a);

    printf("%d",a);

    return 0;
}

Output

Advantages of Pointers

✔ Faster execution

✔ Efficient memory usage

✔ Dynamic memory allocation

✔ Supports data structures

✔ Enables call by reference

Disadvantages

❌ Difficult to understand

❌ Risk of memory leaks

❌ Can cause segmentation faults if misused

Applications of Pointers

Dynamic memory allocation
File handling
Linked lists
Trees
Graphs
Function arguments
Operating systems
Compiler design

📌 Key Points

A pointer stores the address of another variable.
& returns the address of a variable.
* accesses the value stored at the pointed address.
Arrays and pointers are closely related.
Pointers enable efficient memory management and advanced programming techniques.

📘 Computer Fundamentals and Programming with C

Module 5 – Part 2

Structures, Unions, Dynamic Memory Allocation and File Handling

Theory: 15 Lectures

📚 Contents

Structure
Nested Structure
Array of Structures
Union
Difference Between Structure and Union
Dynamic Memory Allocation
malloc()
calloc()
realloc()
free()
File Handling
File Opening Modes
File Functions
EOF

🎯 Learning Outcomes

After studying this chapter, students will be able to:

Create and use structures and unions.
Allocate memory dynamically.
Read and write files in C.
Differentiate between structures and unions.
Develop applications using file handling.

PART-1

STRUCTURE

1. Introduction to Structure

In C programming, variables of different data types often need to be stored together. For example, information about a student includes a roll number (integer), name (string), and percentage (float). Declaring separate variables for each student becomes difficult and inefficient.

A structure allows different data types to be grouped together under a single name.

Definition

A structure is a user-defined data type that groups related variables of different data types under one name.

Real-Life Example

A student's record contains:

Name
Roll Number
Age
Percentage

All these details can be stored in one structure.

Syntax


struct Student
{
    int roll;
    char name[30];
    float marks;
};

Creating Structure Variables


struct Student s1;

Accessing Members

The dot (.) operator is used.

Example


s1.roll=101;

strcpy(s1.name,"Rahul");

s1.marks=88.5;

Complete Program


#include<stdio.h>

struct Student
{
    int roll;
    char name[30];
    float marks;
};

int main()
{
    struct Student s;

    s.roll=101;

    strcpy(s.name,"Amit");

    s.marks=92.5;

    printf("%d\n",s.roll);

    printf("%s\n",s.name);

    printf("%.2f",s.marks);

    return 0;
}

Output


101

Amit

92.50

Advantages of Structures

✅ Groups different data types.

✅ Improves program organization.

✅ Easy data management.

✅ Supports database-like records.

Applications

Student Information System
Employee Database
Library Management
Hospital Management
Banking Software

2. Nested Structure

A structure inside another structure is called a nested structure.

Example


struct Date
{
    int day;
    int month;
    int year;
};

struct Student
{
    int roll;

    struct Date dob;
};

Applications

Employee records
Address management
Date and time storage

3. Array of Structures

An array can store multiple structure variables.

Example


struct Student s[50];

This can store information for 50 students.

Example


s[0].roll=101;

s[1].roll=102;

PART-2

UNION

What is a Union?

A union is also a user-defined data type similar to a structure.

The difference is that all members share the same memory location.

Only one member can hold a valid value at a time.

Definition

A union is a user-defined data type in which all members share the same memory location.

Syntax


union Data
{
    int i;

    float f;

    char name[20];
};

Example


union Data d;

d.i=100;

Structure vs Union

Structure	Union
Separate memory for each member	Shared memory
Large memory usage	Small memory usage
All members active simultaneously	Only one member active at a time
Suitable for records	Suitable for memory optimization

Advantages of Union

✔ Saves memory

✔ Efficient for embedded systems

✔ Useful in device drivers

PART-3

Dynamic Memory Allocation

Introduction

Normally, memory is allocated during compilation.

Sometimes the required memory size is unknown beforehand.

In such situations, memory is allocated during program execution.

This is called Dynamic Memory Allocation.

Advantages

Memory allocated when required.
Better memory utilization.
Flexible programs.
Supports dynamic data structures.

Dynamic Memory Functions

Function	Purpose
malloc()	Allocates memory
calloc()	Allocates and initializes memory
realloc()	Changes memory size
free()	Releases memory

malloc()

Allocates memory but does not initialize it.

Syntax


pointer=(datatype*)malloc(size);

Example


int *p;

p=(int*)malloc(5*sizeof(int));

calloc()

Allocates memory and initializes all bytes to zero.

Syntax


pointer=(datatype*)calloc(number,size);

Example


int *p;

p=(int*)calloc(5,sizeof(int));

realloc()

Changes the size of previously allocated memory.

Syntax


pointer=realloc(pointer,new_size);

Example


p=realloc(p,10*sizeof(int));

free()

Releases allocated memory.

Syntax


free(pointer);

Example


free(p);

Comparison

malloc()	calloc()
No initialization	Initializes with zero
One argument	Two arguments
Faster	Slightly slower

PART-4

File Handling

Introduction

A program stores data in memory temporarily.

When the program ends, the data is lost.

To store data permanently, files are used.

Definition

File handling is the process of storing, reading, and modifying data in files using C programs.

Steps in File Handling


Open File

↓

Read/Write

↓

Close File

File Pointer


FILE *fp;

fopen()

Opens a file.

Syntax


fp=fopen("student.txt","r");

File Modes

Mode	Meaning
r	Read
w	Write
a	Append
r+	Read & Write
w+	Read & Write (Overwrite)
a+	Read & Append

fclose()

Closes the file.

Syntax


fclose(fp);

fprintf()

Writes formatted data into a file.

Example


fprintf(fp,"%d",100);

fscanf()

Reads formatted data.

Example


fscanf(fp,"%d",&x);

fputs()

Writes a string.

Example


fputs("Welcome",fp);

fgets()

Reads a string.

Example


fgets(name,20,fp);

EOF

EOF means End Of File.

It indicates that there is no more data available to read.

Example


while((ch=fgetc(fp))!=EOF)

Advantages of File Handling

✔ Permanent storage

✔ Large data storage

✔ Easy retrieval

✔ Data sharing

✔ Backup facility

Applications

Student Database
Banking System
Payroll System
Library Management
Inventory Management
Hospital Records

📌 Key Points

Structures store different data types together.
Unions share a common memory location.
Dynamic memory is allocated during execution.
malloc(), calloc(), realloc(), and free() manage dynamic memory.
File handling enables permanent storage of data.
Always close files using fclose() after use.

📚 Module 5 Summary

Module 5 introduced advanced programming concepts in C, including pointers, structures, unions, dynamic memory allocation, and file handling. Pointers provide direct access to memory and support efficient programming. Structures organize related data, while unions optimize memory usage. Dynamic memory allocation allows flexible memory management during execution, and file handling enables permanent storage and retrieval of data. Together, these concepts help students build efficient, modular, and real-world C applications.

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Thursday, July 2, 2026

Data Structures using C++ MCQ

📚 MCQ 📚

📚 QUIZ 📚

Data Structures using C++ QUESTION ANSWER

📚 set 📚

COMPUTER SCIENCE NEP SYLLABUS – WBSU SEMESTER 2

🎓 SEMESTER 2

WEST BENGAL STATE UNIVERSITY

C LANGUAGE QUESTION ANSWER

📚 set 📚

C LANGUAGE MCQ

📚 MCQ 📚

📚 QUIZ 📚

SEMESTER 1. CMSACOR01T: Computer Fundamentals and programming with C wbsu syllabus

📘 Computer Fundamentals and Programming with C

Module 1 : Overview of C (Part 1)

📚 Contents

🎯 Learning Objectives

1. Introduction to Programming

What is Programming?

Why Do We Need Programming?

💡 Remember

2. What is C Programming?

Definition

📌 Characteristics of C

3. History of C Programming

👨‍💻 Dennis Ritchie

Major Contributions

🏢 Bell Laboratories

4. Evolution of C Programming

Evolution Flow

5. Why Was C Developed?

6. Features of C Programming

1. Simple

2. Fast

3. Portable

4. Structured

5. Rich Library

6. Middle-Level Language

7. Dynamic Memory Management

7. Advantages of C

8. Applications of C

📌 Key Points

📝 Summary

📘 Computer Fundamentals and Programming with C

Module 1 – Part 2

Basic Structure of a C Program

🎯 Learning Objectives

1. Introduction

2. Basic Structure of a C Program

3. Components of a C Program

(a) Documentation Section

(b) Link Section

(c) Definition Section

(d) Global Declaration Section

(e) main() Function

(f) User-defined Functions

4. First C Program

Output

5. Explanation of the Program

Line 1

Line 2

Line 3

Line 4

Line 5

Line 6

6. Flow of Program Execution

7. Compilation Process

Step 1: Preprocessing

Step 2: Compilation

Step 3: Assembling

Step 4: Linking

8. Header Files

9. The printf() Function

10. The return Statement

11. Comments in C

Single-line Comment

Multi-line Comment