Format into a Bounded Buffer

The supply desk builds a crate label in a fixed-size array before printing it. snprintf takes the buffer capacity, including room for the terminating null character. It returns the number of characters it wanted to write, or a negative value on error. A return value at least as large as the capacity means truncation.

#include <stdio.h>
int main(void) {
    char label[32];
    int written = snprintf(label, sizeof label, "%s #%d", "Crate", 7);
    if (written < 0 || (size_t)written >= sizeof label) return 1;
    puts(label);
    return 0;
}

Run it to see Crate #7. Try changing label[32] to label[8]: the check should reject the truncated result instead of printing a partial label.