c program to find the frequency of all characters in a string

#include <stdio.h>
#define SIZE 256

void findFrequency(char *str) {
    int frequency[SIZE] = {0};

    for (int i = 0; str[i] != '\0'; i++) {
        int index = (int)str[i];
        frequency[index]++;
    }

    printf("Character\tFrequency\n");
    for (int i = 0; i < SIZE; i++) {
        if (frequency[i] != 0) {
            printf("%c\t\t%d\n", i, frequency[i]);
        }
    }
}

int main() {
    char str[] = "hello, world!";
    findFrequency(str);
    return 0;
}