How do you execute a nested for loop in C++?

Let’s start with a simple analogy. Imagine there are 3 lines at a concert, and each line has 5 people in it. For each line, you need to visit each person in that line. The rows are labeled as i and the columns as j.

How can we do this using for-loops?

Here comes the idea of using nested for loops. Using nested allows us to declare a for-loop within the body of another for-loop. The code below shows the syntax of the loop and explains it in detail.

Within the for loop on line 6, another for loop is written in the body on line 8.

1. In simple terms, the for loop on line 6 runs the for loop on line 8 for every value of i.
2. The for loop on line 8 runs till the value of j increases from 0 to 4.
3. Then it moves back to the for-loop on line 6.
4. Steps 1 to 3 are repeated until the value of i is equal to 2.
5. The loop on line 8 cannot run if the loop on line 6 terminates completely.

The slideshow below shows how this loop works when the value of i=0. This same process is repeated when i=1 and i=2.