1. BASIC - CLICK
🎯 What is a for loop?
A for loop in Python is used to repeat a block of code for each item in a sequence (like list, string, range, etc.).
📌 Definition
A
forloop is used to iterate over a sequence (list, tuple, string, range) and execute code repeatedly.
🧠 Basic Syntax
for variable in sequence:
# code block
🔢 1. Using range() (Most Important)
Example 1: Print 1 to 5
for i in range(1, 6):
print(i)
Output:
1
2
3
4
5
Example 2: Print Even Numbers
for i in range(2, 11, 2):
print(i)
Output:
2
4
6
8
10
📌 range() Explanation
range(start, stop, step)
| Parameter | Meaning |
|---|---|
| start | Starting number |
| stop | Ending number (not included) |
| step | Increment value |
📚 2. Looping through a List
fruits = ["apple", "banana", "mango"]
for fruit in fruits:
print(fruit)
Output:
apple
banana
mango
🔤 3. Looping through a String
for letter in "Python":
print(letter)
Output:
P
y
t
h
o
n
🔁 4. Using for with if (Very Important)
Example: Print numbers greater than 5
for i in range(1, 11):
if i > 5:
print(i)
Output:
6
7
8
9
10
🧠 5. Nested for Loop
(Loop inside loop)
Example: Multiplication Table
for i in range(1, 4):
for j in range(1, 4):
print(i * j, end=" ")
print()
Output:
1 2 3
2 4 6
3 6 9
⚡ Advantages of for Loop
- Easy to use
- Reduces code length
- Works with sequences
- Useful for arrays, lists, strings
❌ Disadvantages
- Not suitable for unknown repetition count (use
whileloop instead)
🆚 for loop vs while loop
| Feature | for loop | while loop |
|---|---|---|
| Usage | Known range | Unknown condition |
| Structure | Simple | More flexible |
| Control | Automatic iteration | Manual control |
📌 Real-Life Example
- Counting students in class 👨🎓
- Printing attendance list 📋
- Iterating shopping items 🛒
📘 Summary
forloop is used for repeating tasks- Works with range, lists, strings, etc.
- Very important for programming and algorithms
- Commonly used in sorting and searching programs
❓ Important Questions
Short Questions
- What is a for loop?
- What is range() function?
- Write syntax of for loop.
- What is nested for loop?
- Give one example of for loop.
Long Questions
- Explain for loop with example.
- Write program using for loop to print numbers 1 to 10.
- Explain nested for loop with example.
- Compare for loop and while loop.
- Write a program using for loop for multiplication table.
1. Print 1 to 10
for i in range(1, 11):
print(i)
2. Print 10 to 1 (Reverse)
for i in range(10, 0, -1):
print(i)
3. Print Even Numbers (1 to 20)
for i in range(2, 21, 2):
print(i)
4. Print Odd Numbers (1 to 20)
for i in range(1, 21, 2):
print(i)
5. Sum of 1 to 10
sum = 0
for i in range(1, 11):
sum += i
print(sum)
6. Multiplication Table of 5
for i in range(1, 11):
print(5, "x", i, "=", 5*i)
7. Factorial of a Number
n = 5
fact = 1
for i in range(1, n+1):
fact *= i
print(fact)
8. Fibonacci Series
a, b = 0, 1
for i in range(10):
print(a)
a, b = b, a + b
9. Square of Numbers (1 to 10)
for i in range(1, 11):
print(i*i)
10. Cube of Numbers (1 to 10)
for i in range(1, 11):
print(i*i*i)
11. Count Even Numbers (1 to 50)
count = 0
for i in range(1, 51):
if i % 2 == 0:
count += 1
print(count)
12. Sum of Even Numbers (1 to 20)
sum = 0
for i in range(2, 21, 2):
sum += i
print(sum)
13. Print Characters of String
for ch in "Python":
print(ch)
14. Reverse Loop Printing List
arr = [10, 20, 30, 40]
for i in range(len(arr)-1, -1, -1):
print(arr[i])
15. Find Maximum in List
arr = [10, 50, 20, 80, 30]
max = arr[0]
for i in arr:
if i > max:
max = i
print(max)
16. Find Minimum in List
arr = [10, 50, 20, 80, 5]
min = arr[0]
for i in arr:
if i < min:
min = i
print(min)
17. Print All Elements of List
arr = [1, 2, 3, 4, 5]
for i in arr:
print(i)
18. Sum of List Elements
arr = [10, 20, 30, 40]
sum = 0
for i in arr:
sum += i
print(sum)
19. Print Multiples of 3 (1 to 30)
for i in range(3, 31, 3):
print(i)
20. Print Pattern (Stars)
for i in range(1, 6):
print("*" * i)
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