how to change file permissions in C language

#include <stdio.h>
#include <sys/stat.h>

int main() {
    char *filename = "example.txt";
    int result = chmod(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    if (result == 0) {
        printf("File permissions changed successfully.\n");
    } else {
        printf("Error changing file permissions.\n");
    }
    return 0;
}