While Loop and For Loop in Python

Introduction

Loops are an essential part of programming, allowing us to execute a block of code multiple times. Python provides two main types of loops: the while loop and the for loop. This article explains these loops with examples.

While Loop

The while loop continues to execute a block of code as long as the condition specified is true. It is used when the number of iterations is not known in advance.

Syntax

    while condition:
        # code to execute
        

Example

The following example prints numbers from 1 to 5 using a while loop:

    # Example of while loop
    count = 1
    while count <= 5:
        print(count)
        count += 1
        

Output:

    1
    2
    3
    4
    5
        

For Loop

The for loop is used to iterate over a sequence (like a list, tuple, dictionary, set, or string) or a range of numbers.

Syntax

    for variable in sequence:
        # code to execute
        

Example

The following example prints each element of a list using a for loop:

    # Example of for loop
    numbers = [1, 2, 3, 4, 5]
    for num in numbers:
        print(num)
        

Output:

    1
    2
    3
    4
    5
        

Using Range in For Loop

The range() function is commonly used with for loops to iterate over a sequence of numbers. It can take up to three arguments: start, stop, and step.

Example

The following example prints numbers from 0 to 4 using a range:

    # Example of for loop with range
    for i in range(5):
        print(i)
        

Output:

    0
    1
    2
    3
    4
        

Comparison of While Loop and For Loop

Both while and for loops are used to repeat a block of code, but they are suited for different use cases:

• Use a while loop when the number of iterations is not known in advance and depends on a condition.
• Use a for loop when iterating over a sequence or a range of numbers.

Conclusion

Understanding the differences between while and for loops and knowing when to use them is crucial for efficient programming. Experiment with these examples to gain more confidence.