for-loops.md

For loops

For loops provide a more concise way of iterating.

A for loop is made up of an initialise statement, this sets up the counter variable.

int i = 0;

A condition statement, tests for counter variable.

i < 5;

Update statement, increments the counter variable.

i++

All on one line:

for (int i = 0; i < 5; i++)

Note: The i variable only exists inside the for loop. This is know as a variables scope.

Simple For loop example

#include <stdio.h>

int main(void)
{

    for (int i = 0; i < 5; i++)
        printf("i: %d\n", i);
    return 0;

}

Output:

i: 0
i: 1
i: 2
i: 3
i: 4

for loop with break

The break keyword can be used inside a for loop block. This will end the iteration when a condition is true.

for (int i = 0; i < 5; i++)
{
    printf("i: %d\n", i);
    if (i == 2) break; // loop ends when i == 2
}

Output

i: 0
i: 1
i: 2

for loop with continue

The continue keyword can be used inside a for loop block. This will skip over the loop body when a condition is true, and restart the iteration.

for (int i = 0; i < 5; i++)
{
    if (i == 2) continue; // skips the remaining when i == 2
    printf("i: %d\n", i); // skipped if i == 2
}

Output

i: 0
i: 1
i: 3
i: 4