How do nested loops work in Python?

Nested loops in Python are loops within loops. They allow you to iterate over multiple sequences or perform repeated actions in a structured manner. Here's how they work:

Structure

A nested loop consists of an outer loop and one or more inner loops. The inner loop runs completely for each iteration of the outer loop.

Example

Here's a simple example using nested for loops:

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

Output

This will produce:

i: 0, j: 0
i: 0, j: 1
i: 1, j: 0
i: 1, j: 1
i: 2, j: 0
i: 2, j: 1

Explanation

The outer loop (for i in range(3)) runs 3 times (for i = 0, 1, 2).
For each iteration of the outer loop, the inner loop (for j in range(2)) runs 2 times (for j = 0, 1).
This results in a total of 3 * 2 = 6 iterations.

Use Cases

Nested loops are useful for tasks like:

Creating multi-dimensional arrays (e.g., matrices).
Generating combinations or permutations.
Iterating through lists of lists.

If you have any specific scenarios in mind or need further examples, feel free to ask!