count-sort.c

void count_sort(char *str)
{
    int count[256];// all chars
    char output[strlen(str)];
    memset(count, 0, sizeof(count));
    for (int i = 0; str[i]; i++) 
        count[str[i]]++;
    for (int i = 1; i < 256; i++)
        count[i]+=count[i-1];
    for (int i = 0; str[i]; i++)
    {
        output[count[str[i]]-1] = str[i];
        count[str[i]]--;
    }
    for (int i = 0; str[i]; i++) {
        str[i] = output[i];     
    }
}
void counting_sort(char *str)
{
    int count[256];
    memset(count, 0, sizeof(count));
    for (int i = 0;str[i]; i++)
        count[str[i]]++;
    int j = 0;
    for (int i = 0; i < 256; i++)
        while(count[i]--)
            str[j++] = i;
    str[j]='\0';
}