C - Nested loop

Nested loop is a loop inside another loop, it is useful when you want to print numbers in rows and columns form like in 2d arrays or to print a pattern.

Example 1: Nested for loop.

for (i=1; i<=10; i++)
{
    for (j=1; j<=10; j++)
    {
        printf("%d\n", a++);
    }
}

The above code will execute up to 100 times.

Example 2: Nested while loop.

int i=1, j=1, a=1; 
while (i<=10)
{
    while (j<=10)
    {
        printf("%d\n", a++);
        j++;
    }
    i++;
}

The above code will execute up to 100 times.

Example 3: Nested do while loop.

int i=1, j=1, a=1; 
do{
    do{
        printf("%d\n", a++);
        j++;
    }while (j<=10);
    i++;
}while (i<=10);

The above code will execute up to 100 times.

How to use Nested Loop