Break and Continue

for and while loops do their job from start to finish. But what if, in the middle of a loop, we want to say "ok, that's enough, stop"? Or "skip this one, go to the next"?

C gives us two keywords for this: break and continue

break stops the loop completely. The remaining iterations never happen

#include <stdio.h>

int main(void) {
    for (int i = 0; i < 100; i++) {
        if (i == 5) {
            break;
        }
        printf("%d\n", i);
    }
    return 0;
}

Output

We told the loop to go up to 99, but as soon as i became 5, break kicked in and the loop ended

A real example: searching for a value in an array

#include <stdio.h>

int main(void) {
    int values[] = { 10, 25, 7, 42, 13 };
    int n = sizeof(values) / sizeof(values[0]);
    int target = 42;

    for (int i = 0; i < n; i++) {
        if (values[i] == target) {
            printf("Found %d at position %d\n", target, i);
            break;
        }
        printf("Checking %d...\n", values[i]);
    }
    return 0;
}

The loop stops as soon as we find what we're looking for. break saves us time

continue is different. It doesn't stop the loop; it just skips the rest of the current iteration and moves on to the next one

#include <stdio.h>

int main(void) {
    for (int i = 0; i < 10; i++) {
        if (i == 5) {
            continue;
        }
        printf("%d\n", i);
    }
    return 0;
}

Output

5 is missing. When i was 5, continue skipped over printf and the loop kept going

A real example: print only even numbers

#include <stdio.h>

int main(void) {
    for (int i = 0; i <= 10; i++) {
        if (i % 2 != 0) {
            continue;
        }
        printf("%d\n", i);
    }
    return 0;
}

Output: 0 2 4 6 8 10

Both keywords work the same way in while, not just for

#include <stdio.h>

int main(void) {
    int i = 0;
    while (1) {   // remember: 1 is "true" in C
        if (i >= 5) {
            break;
        }
        printf("%d\n", i);
        i++;
    }
    return 0;
}

while (1) would normally be infinite, but break lets us escape

A small warning: break and continue can make code harder to read if you abuse them. Use them when they make the logic clearer, not just to look clever

Mission: The Punch Card Room Inspection

You are doing the annual inspection of the punch card reader room, numbered from 1 to 20. One reader is marked sealed for repairs: it must be skipped with continue, without printing it. Another reader triggers the smoke alarm: the moment you reach it, you stop the inspection with break (without printing it either).

Read two integers from input: sealed and alarm
Walk through readers 1 to 20 with a for loop
If the current number equals sealed, skip it with continue
If the current number equals alarm, stop the loop with break
Otherwise, print the reader number

Example

Input

13 17

Output

Example

Input

5 10

Output