6.4 Nested-Loops

for (int i = 1; i <= 10; i++)
{
	for (int j = 1; j <= 10; j++)
	{
		printf(“%d\t”, (i*j));
	}
	printf(“\n”);
}

In the above example, we have used 2 for loops to create a multiplication table for the numbers between 1 and 10. The first for loop iterates through each number from 1 through 10, increasing i by 1 every iteration. The second for loop, which is inside the first for loop, has the same for loop header as the first for loop, except it uses a different variable, j. Inside this for loop, the computer prints out the product of i and j. The second for loop is repeated 10 times with every 1 iteration of the first for loop. After the computer is done reading through the second for loop, it prints a new line before going back to the first for loop. So, essentially, by the time this program has completely finished executing, the first for loop will have ran 10 times and the second for loop will have ran 100 times. Here is what the output should look like:

1 2	3	4	5	6	7	8	9	10
2	4	6	8 10 12	14 16 18 20
3	6	9	12 15 18 21 24 27 30
4	8	12 16	20 24 28 32 36 40
5	10 15	20 25	30 35	40 45	50
6	12 18	24 30	36 42 48 54	60
7 14 21 28 35 42 49 56 63 70
8 16 24 32 40 48 56 64 72 80
9 18 27 36 45 54 63 72 81 90
10 20 30 40 50 60 70 80 90 100