Nested Loops in C: Definition & Example

In C programming language, nested loops refer to the structure of having one loop inside another loop or multiple loops. With nested loops, you can execute one iteration of the outer loop in each iteration of the inner loop. This structure allows for the repeated execution of a segment of code at different levels, enabling more flexible and complex control flow.

Here is a simple example demonstrating the use of nested loops to output a multiplication table of nine.

#include <stdio.h>

int main() {
    int i, j;

    for (i = 1; i <= 9; i++) {
        for (j = 1; j <= i; j++) {
            printf("%d * %d = %d\t", j, i, i * j);
        }
        printf("\n");
    }

    return 0;
}

In the example above, the outer loop for (i = 1; i <= 9; i++) is responsible for controlling the number of rows, while the inner loop for (j = 1; j <= i; j++) is responsible for controlling the multiplication table expressions outputted on each row. By using nested loops, we can sequentially print out the multiplication tables from 1 to 9.

It is important to pay attention when using nested loops in order to carefully control the iteration count of the inner and outer loops to avoid infinite loops and performance issues. Additionally, properly using nested loops can simplify program logic, improve code reusability, and enhance readability.