For Loops


For loops in C are straightforward. They supply the ability to create a loop - a code block that runs multiple times. For loops require an iterator variable, usually notated as i.

For loops give the following functionality:

  • Initialize the iterator variable using an initial value
  • Check if the iterator has reached its final value
  • Increases the iterator

For example, if we wish to iterate on a block for 10 times, we write:

int i; for (i = 0; i < 10; i++) { printf("%d\n", i); }

This block will print the numbers 0 through 9 (10 numbers in total).

For loops can iterate on array values. For example, if we would want to sum all the values of an array, we would use the iterator i as the array index:

int array[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; int sum = 0; int i; for (i = 0; i < 10; i++) { sum += array[i]; } /* sum now contains a[0] + a[1] + ... + a[9] */ printf("Sum of the array is %d\n", sum);