Flowcharting,

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🐍 FLOWCHART

Graphical Representation of Program Logic

1. What is a Flowchart?

A Flowchart is a graphical representation of an algorithm or process. It uses standard symbols and arrows to represent the sequence of operations and decision-making steps in a program.

A flowchart helps a programmer understand the logic of a problem before writing the actual Python program.

Basic Idea:
Problem → Algorithm → Flowchart → Program → Output

2. Purpose of a Flowchart

• To represent program logic visually.
• To make complex problems easier to understand.
• To plan a program before coding.
• To identify logical errors.
• To explain a program to others.
• To document the program.
• To help in debugging and testing.

3. Standard Flowchart Symbols

START / END

Terminator

Represents the beginning or termination of a program.

PROCESS

Process

Represents a calculation or processing operation.

INPUT / OUTPUT

Input / Output

Represents data input or output.

?

Decision

Represents a condition with different possible outcomes.

→

Flow Line

Shows the direction of program execution.

4. Basic Flowchart Structure

START

↓

INPUT

↓

PROCESS

↓

OUTPUT

↓

END

5. Example 1 – Addition of Two Numbers

Problem

Take two numbers as input and calculate their sum.

Algorithm

1. Start.
2. Input two numbers A and B.
3. Calculate SUM = A + B.
4. Display SUM.
5. Stop.

Flowchart

START

↓

INPUT A, B

↓

SUM = A + B

↓

DISPLAY SUM

↓

END

Python Program

a = int(input("Enter first number: "))
b = int(input("Enter second number: "))

sum = a + b

print("Sum =", sum)

Output

Enter first number: 10 Enter second number: 20 Sum = 30

6. Example 2 – Even or Odd

Problem

Determine whether a given number is even or odd.

Flowchart

START

↓

INPUT N

↓

N % 2 == 0?

YES

↓

PRINT EVEN

NO

↓

PRINT ODD

↓

END

Python Program

n = int(input("Enter a number: "))

if n % 2 == 0:
    print("Even Number")
else:
    print("Odd Number")

Output

Enter a number: 15 Odd Number

7. Example 3 – Loop Flowchart

Flowcharts can represent repetition or looping operations.

Problem

Display numbers from 1 to 5.

Flowchart

START

↓

i = 1

↓

i ≤ 5?

YES ↓

PRINT i

↓

i = i + 1

↺

Repeat until condition becomes FALSE

↓

END

Python Program

for i in range(1, 6):
    print(i)

Output

1 2 3 4 5

8. Advantages of Flowchart

✅ Advantages

• Easy to understand.
• Provides a visual representation of logic.
• Helps in program planning.
• Makes complex logic easier to understand.
• Helps identify logical errors.
• Useful for debugging.
• Improves communication among programmers.
• Useful for teaching programming.
• Provides program documentation.
• Language independent.

❌ Disadvantages

• Creating large flowcharts can be time-consuming.
• Complex programs may require very large diagrams.
• Modification can be difficult.
• Large flowcharts require more space.
• Flow lines may cross in complex diagrams.
• Not every programming detail is easy to represent.
• Maintenance of large flowcharts can be difficult.
• A major program change may require redrawing.

9. Rules for Drawing a Flowchart

1. Use standard flowchart symbols.
2. Begin with a START symbol.
3. End with an END symbol.
4. Use arrows to indicate the direction of flow.
5. Normally draw the flow from top to bottom or left to right.
6. Use the diamond symbol for decisions.
7. Clearly label decision branches such as YES and NO.
8. Avoid unnecessary crossing of flow lines.
9. Keep the flowchart simple and readable.
10. Use meaningful descriptions inside each symbol.

10. Algorithm vs Flowchart

Algorithm	Flowchart
Written step-by-step procedure.	Graphical representation of the procedure.
Uses words and statements.	Uses symbols and arrows.
Usually easier to write.	Usually easier to visualize.
Good for describing detailed steps.	Good for showing program flow.
Can be modified relatively easily.	Modification may require redrawing.

11. Important Points for Examination

• Flowchart is a graphical representation of an algorithm.
• Oval represents Start or End.
• Rectangle represents Process.
• Parallelogram represents Input or Output.
• Diamond represents Decision.
• Arrows indicate the direction of flow.
• Flowcharts are useful for program planning.
• Flowcharts help in understanding and debugging program logic.
• Flowcharts can represent sequence, selection and repetition.

12. Quick Summary

Flowchart = Graphical representation of an algorithm or program logic.

Important Symbols:
🟢 Oval → Start / End
▭ Rectangle → Process
▱ Parallelogram → Input / Output
◇ Diamond → Decision
→ Arrow → Direction of Flow

Program Development:
Problem → Algorithm → Flowchart → Python Program → Output

© Educational Programming Notes | Created by Bijan Krishna Paul

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