Hashmap

This is an implementation of the HashMap data structure.

initialization and destruction:

Map * new_map();

creates a new map, returns its pointer.

• first parameter is the initial size
• second parameter is the function to compare keys
• third parameter is the function to generate hashes for keys

void delete_map();

deletes the map

---

working with a map: the following functions first parameter is always the pointer to an initialized map.

void map_put();

creates a new entry in the map

• second parameter is the key
• third parameter is the value

returns nothing.

void *map_get();

gets the value from an entry

• second parameter is the key of an entry

returns NULL if entry not found for key

void *map_remove();

removes an entry from the map

• second parameter is the key of an entry

returns the value of the entry after remove, returns NULL if entry not found.

int map_contains(); returns if an entry was found for the given key.

• second parameter is the key of an entry

returns true if an entry was found, false otherwise.

int map_isempty();

returns true if the given map is empty, returns false if not.

---

usage:

the following example uses strings as key and value

#include "HashArray.h"

int strhash(char *str){
    int hash = 1, i;
    for(i = 0; s[i]; i++){
        hash = (hash * 10) + s[i];
    }
    return hash;
}


int main(){
    Map *mymap = new_map(10, strcmp, strhash);
    printf("is the map empty? -%s", map_isempty(mymap) ? "yes" : "no");
   
    //put an element in the map:
    map_put(mymap, "key", "value");
    printf("%s\n", map_get("key"));    
    printf("is the map empty? -%s", map_isempty(mymap) ? "yes" : "no");        
    map_remove(mymap, "key");
    printf("%s\n", map_get("key"));
    printf("is the map empty? -%s", map_isempty(mymap) ? "yes" : "no");
    return 0;
}