Introduction to Loops

Loops in Python are used to repeat a block of code multiple times.

Instead of writing the same code again and again, we use loops to make programs short, simple, and efficient.

Real-Life Example

Loops are like daily activities:

• Brushing teeth every day
• Counting numbers
• Repeating homework practice

Why Use Loops?

• Saves time and effort
• Reduces repeated code
• Makes programs efficient
• Helps in solving problems easily

Types of Loops in Python

1. for Loop

The for loop is used to repeat code a fixed number of times.

 It is commonly used when we know how many times we want to repeat something.

Example

for i in range(5):
    print(i)

Output

0
1
2
3
4

The loop runs 5 times

2. while Loop

The while loop is used to repeat code until a condition becomes False

 It is used when we don’t know how many times the loop will run.

Example

x = 0

while x < 5:
    print(x)
    x += 1

Output

0
1
2
3
4

Loop runs until x < 5 becomes False

Difference Between for and while

Common Beginner Mistakes

•  Infinite loop in while
•  Wrong indentation
•  Forgetting to update variable
• Wrong range values

➤ Key Points

• Loops repeat code multiple times
• for loop → fixed repetitions
• while loop → condition-based
• Helps reduce code length
• Improves logic building

➤ Tips

• Use for loop when count is known
• Use while loop when condition is needed
• Avoid infinite loops
• Practice with small examples