This always prints 'none'

const_switch.c

#include <stdio.h>

const char *example(int num) {
    const char *str;

    switch (num) {
        case 1:
            str = "one";
        case 2:
            str = "two";
        case 3:
            str = "three";
        default:
            str = "none";
    }

    return str;
}

int main(int argc, char **argv) {
    printf("%s\n", example(2));

    return 0;
}

you need break;