The while loop in Python is a control flow statement that allows code to be executed repeatedly based on a given condition. It’s especially useful when the number of iterations is not known in advance.

Syntax of a While Loop

while condition:
    # Code block to execute

• condition: The loop will keep executing as long as this condition is True.
• The code inside the loop should eventually make the condition False to avoid an infinite loop.

How a While Loop Works

1. The condition is checked first.
2. If the condition is True, the code inside the loop runs.
3. After each iteration, the condition is checked again.
4. When the condition becomes False, the loop stops.

Example 1: Basic While Loop

count = 1 # Initialization
while count <= 5: # Condition
    print("Count:", count)
    count += 1 # Update the variable

Output:

Count: 1
Count: 2
Count: 3
Count: 4
Count: 5

Explanation:

• The loop starts with count = 1.
• Each time the loop runs, count is incremented by 1.
• The loop stops when count > 5.

Example 2: Using a While Loop for User Input

password = "" # Initialize variable
while password != "1234": # Condition
    password = input("Enter the correct password: ")
print("Access granted!")

Output (Example Input):

Enter the correct password: 5678
Enter the correct password: 1234
Access granted!

Explanation:

• The loop keeps asking for input until the user enters the correct password.

Example 3: Breaking Out of a While Loop

Sometimes, you might need to exit a loop prematurely using the break statement.

while True: # Infinite loop
    num = int(input("Enter a positive number (or -1 to stop): "))
    if num == -1: # Break condition
        print("Exiting the loop!")
        break
    print(f"You entered: {num}")

Output (Example Input):

Enter a positive number (or -1 to stop): 5
You entered: 5
Enter a positive number (or -1 to stop): -1
Exiting the loop!

Example 4: Using a While Loop with Else

The else block runs when the loop condition becomes False.

counter = 1
while counter <= 3:
    print("Counter:", counter)
    counter += 1
else:
    print("Loop ended!")

Output:

Counter: 1
Counter: 2
Counter: 3
Loop ended!

Explanation:

• The else block runs after the loop ends naturally.

Key Points to Remember

1. The while loop is ideal for scenarios where you don’t know the number of iterations in advance.
2. Always update variables inside the loop to prevent infinite loops.
3. Use break to exit a loop early and else to run code after the loop ends.