Python nested loop

In Python, a nested loop refers to having one loop inside another. Both loops can be of the same type (for or while) or different types. Nested loops are useful for iterating over multi-dimensional data, such as matrices or lists of lists, or performing operations where one set of iterations is dependent on another.

Usage of nested loop

Example 1: Nested for loops

for i in range(3):  # Outer loop
    for j in range(2):  # Inner loop
        print(f"i = {i}, j = {j}")

Explanation: The outer loop (i) runs 3 times, and for each iteration of i, the inner loop (j) runs 2 times. This results in a total of 6 iterations in total.

Output:

i = 0, j = 0
i = 0, j = 1
i = 1, j = 0
i = 1, j = 1
i = 2, j = 0
i = 2, j = 1

Example 2: Nested while loop

i = 1
while i <= 3:  # Outer loop
    j = 1
    while j <= 2:  # Inner loop
        print(f"i = {i}, j = {j}")
        j += 1
    i += 1

Explanation: The outer while loop runs as long as i is less than or equal to 3, and the inner while loop runs twice for each value of i. Each iteration of the inner loop increments j, and after the inner loop completes, the outer loop increments i.