finished? map

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>

struct Map {
    int length;
    int allocated;
    char **keys;
    char **values;
};

struct Map *Map_create()
{
    struct Map *map = malloc(sizeof(struct Map));
    assert(map != NULL);

    map->allocated = 0;
    map->length = 0;
    map->keys = NULL;
    map->values = NULL;

    return map;
}

char* Map_get(struct Map *map, char *key)
{
    assert(map != NULL);

    int i;

    for(i = 0; i < map->length; i++){
        if(strcmp(key, map->keys[i]) == 0){
            return map->values[i];
        }
    }

    return NULL;
}

int Map_get_key_index(struct Map *map, char *key)
{
    assert(map != NULL);
    int i;

    for(i = 0; i < map->length; i++){
        if(strcmp(key, map->keys[i]) == 0){
            return i;
        }
    }

    return -1;
}

int Map_contains_key(struct Map *map, char *key)
{
    assert(map != NULL);
    int i;

    for(i = 0; i < map->length; i++){
        if(strcmp(key, map->keys[i]) == 0){
            return 1;
        }
    }

    return 0;
}

int Map_contains_value(struct Map *map, char *value)
{
    assert(map != NULL);
    int i;

    for(i = 0; i < map->length; i++){
        if(strcmp(value, map->values[i]) == 0){
            return 1;
        }
    }

    return 0;
}

void Map_remove(struct Map *map, char *key)
{
    assert(map != NULL);

    // check if key exists and get its index
    int k = Map_get_key_index(map, key);
    int i = 0;

    if(k > -1){
        // map is now shorter
        map->length--;

        // shift all the key/values pairs
        // after the "erased pair" upwards
        for(i = k; i < map->length; i++){
            map->keys[i] = map->keys[i+1];
            map->values[i] = map->values[i+1];
        }
    }
}

void Map_put(struct Map *map, char *key, char *value)
{
    assert(map != NULL);
    int i = Map_get_key_index(map, key);
    int k; // index of the new key/value pair

    if(i > -1){
        // will overwrite existing value if key already exists
        k = i;
    }else{
        // will add a new key/value pair

        // check if there's enough space
        if(map->length == map->allocated){

            // allocate more space
            if(map->allocated == 0){
                // begin allocating 2
                map->allocated = 2;
            }else{
                // double if more is needed
                map->allocated *= 2;
            }

            void *tmp_keys = realloc(map->keys, map->allocated * sizeof(key));
            void *tmp_values = realloc(map->values, map->allocated * sizeof(value));

            map->keys = (char**)tmp_keys;
            map->values = (char**)tmp_values;
        }

        // increase the length
        k = map->length;
        map->length = k + 1;
    }

    // write key/value pair to k index
    map->keys[k] = key;
    map->values[k] = value;
}