What do break and continue do in loops?

break jumps out of the loop completely; continue skips the rest of the current iteration and jumps to the loop's next test/update.

// break - exit loop immediately
while (i < N) {
    c += a[i];
    // Done, exit the loop
    if (c > N) break;
    i++;
}

// continue - skip rest of body, go to next iteration
for (i = 0; i < N; i++) {
    // Skip odd numbers
    if (i % 2) continue;
    // Only even indices
    c += a[i];
}

With nested loops:

for (i = 0; i < N; i++) {
    for (j = 0; j < M; j++) {
        // Only exits inner loop!
        if (condition) break;
    }
    // Continues here after inner break
}

Tip: To break out of nested loops, use a flag variable, goto, or refactor into a function with return.