Hashmap

hashmap.c

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

#define MAX_KEY 50
#define MAX_HASH 10

typedef struct node {
	char key[MAX_KEY];
	int value;
	struct node *next;
} node;

int hash_func(char key[], int hash_max)
{
	// Adds up char values of key and then does a modulus on the hash size
	int total = 0;
	int i, len;
	len = strlen(key);
	for(i = 0; i < len; i++)
		{
			total += (int) key[i];
		}
	return total % hash_max;
}

int put_int(node *hash_array[], int hash_max, char key[], int value)
{
	// constructs a new node and puts it into the array at the head of the linked list
	int index = hash_func(key, hash_max);
	printf("Putting %s into hash at index %d\n", key, index);

	node new;
	new.value = value;
	strcpy(new.key, key);
	new.next = hash_array[index];
	hash_array[index] = &new;
	return 0;
}

int *get_int_ptr(node *hash_array[],  int hash_max, char key[])
{
	// goes through linked list at the index and outputs the int if it exists
	int index = hash_func(key, hash_max);
	node *curr = hash_array[index];
	printf("Looking for %s in hash\n", key);
	while(curr != NULL)
		{
			printf("At node with key %s and value %d\n", curr->key, curr->value);
			if(strcmp(curr->key, key) == 0) 
				{
					int *ans;
					ans = &(curr->value);
					return ans;
				}
			else {
				curr = curr->next;
			}
		}
	return NULL;
}

int init_hash(node *hash_array[], int hash_max)
{
	//fills a hash array with empty structs
	struct node empty;
	empty.key[0] = '\0';
	empty.value = 0;
	empty.next = NULL;
	int i;
	for(i = 0; i++; i < hash_max)
		{
			hash_array[i] = &empty;
		}
	return 0;
}

int main()
{
	//make and init hash array
	node *hash_array[MAX_HASH];
	init_hash(hash_array, MAX_HASH);
	//put some values in.  two and three go to same bucket
	put_int(hash_array, MAX_HASH, "one", 1);
	put_int(hash_array, MAX_HASH, "two", 2);
	put_int(hash_array, MAX_HASH, "three", 3);
	// get an int pointer back as answer
	int *ans_ptr = get_int_ptr(hash_array,  MAX_HASH, "two");
	// make sure it isn't null
	if(ans_ptr != NULL) {
		int ans = *ans_ptr;
		printf("%d\n", ans);
	}
	else {
		printf("Not found\n");
	}
	return 0;
}