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);
Exercise
Calculate the factorial (multiplication of all items array[0] to array[9], inclusive), of the variable array.
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