In C++, you can nest loops within each other to create complex iterations. This is known as nested looping. The most common type of nested loop is the nested for loop.

Here's an example of a nested for loop:

for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 2; j++) {
        cout << "i: " << i << ", j: " << j << endl;
    }
}

In this example, there are two for loops nested within each other. The outer loop iterates over the values of i from 1 to 3, and the inner loop iterates over the values of j from 1 to 2. The code inside the inner loop is executed for each iteration of the outer loop.

The output of this code will be:

i: 1, j: 1
i: 1, j: 2
i: 2, j: 1
i: 2, j: 2
i: 3, j: 1
i: 3, j: 2

You can nest any type of loop within another loop, including while loops and do-while loops. However, be careful when nesting loops, as it can lead to complex and hard-to-read code. If possible, try to simplify your code by using other programming techniques.