Python while Loop

In Python, a while loop is used to repeatedly execute a block of code as long as a certain condition is true. The basic syntax of a while loop in Python is:

while condition:
    # execute this block of code as long as the condition is true

Here, condition is any expression that can be evaluated to True or False. The block of code inside the while loop is executed repeatedly as long as the condition is True. When the condition becomes False, the program moves on to the next statement after the while loop.

For example, here's a simple while loop that counts from 1 to 5 and prints each number:

i = 1

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

Output:

1
2
3
4
5

In this example, the while loop executes as long as the value of i is less than or equal to 5. The value of i is initially set to 1, and each time through the loop, the value of i is incremented by 1. The loop continues until the value of i is greater than 5.

You should be careful when using a while loop to avoid infinite loops. An infinite loop is a loop that never terminates because the condition is always True. Here's an example of an infinite loop:

while True:
    print("Hello, world!")

This loop will continue to print "Hello, world!" indefinitely because the condition True is always true. To stop an infinite loop, you can use Ctrl-C to interrupt the program.

You can also use the break statement to exit a loop prematurely if a certain condition is met. Here's an example:

i = 1

while i <= 5:
    if i == 3:
        break
    print(i)
    i += 1

Output:

1
2

In this example, the while loop executes as long as the value of i is less than or equal to 5, but when the value of i is equal to 3, the break statement is executed, and the loop is exited prematurely. As a result, only the values of i less than 3 are printed to the console.