Simple generic bisect

main_bisect.c

#include <stdio.h>

#define array_len(x) ((sizeof (x) == 0) ? (0) : (sizeof (x) / sizeof (x[0])))

char *my_word_list[] = {
    "abc",
    "bcd",
    "def",
    "fgh"
};

int my_int_list[] = {
    7,
    12,
    16,
    17,
    32,
    45,
    46,
    48
};

int before_by_int(int *a, int *b) {
    return *b - *a;
}

int before_by_str(char *a, char *b) {
    char *_a = a;
    char *_b = b;
    char a_value;
    char b_value;
    
    while (1) {
        if (!*_a && !*_b) {
            return 0;
        }
        
        if (!*_a) {
            return (int) *_b;
        }
        
        if (!*_b) {
            return (int) -*_a;
        }
        
        a_value = *_a;
        b_value = *_b;
        
        if (a_value != b_value) {
            return (int) b_value - a_value;
        }
        
        _a++;
        _b++;
    } 
    
    return *b - *a;
}

int bisect(void* element, void* a_list[], int list_len, int (*compare)(void* a, void* b)) {
    int start = 0;
    int end = list_len;
    int position = 0;
    void* found = 0;
    int compare_result = 0;
    
    while (1) {
        position = (end - start) / 2 + start;
        found = a_list[position];
        compare_result = compare(found, element);
        
        if (compare_result == 0) {
            return position;
        }
        
        if (position <= start || position >= end) {
            return -1;
        }
        
        if (compare_result > 0) {
            start = position;
            continue;
        }
        
        end = position;
    }
}

int main()
{
    char *my_string = "bcd";
    
    int my_list_len = array_len(my_word_list);
    for (int i = 0; i < my_list_len; i++) {
        printf("%d: %s\n", i, my_word_list[i]);
    }
    
    int element_index = bisect(
        (void*) my_string, 
        (void**) my_word_list, 
        my_list_len, 
        (int (*) (void*, void*)) before_by_str
    );
  
    printf("Bisect index: %d\n", element_index);
    return 0;
}