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This is an easy-to-use hash implementation for C programmers.
Example 1. Adding an item to a hash. 
#include "uthash.h"

struct my_struct {
    int id;                  /* we'll use this field as the key */
    char name[10];             
    UT_hash_handle hh;       /* makes this structure hashable */
};

struct my_struct *users = NULL;

void add_user(struct my_struct *s) {
    HASH_ADD_INT( users, id, s );    
}
Example 2. Looking up an item in a hash. 
struct my_struct *find_user(int user_id) {
    struct my_struct *s;

    HASH_FIND_INT( users, &user_id, s );  
    return s;
}
Example 1. Deleting an item from a hash. 
void delete_user(struct my_struct *user) {
    HASH_DEL( users, user);  
}
This hash can work with any kind of key, not just integer keys as shown here. For a more thorough explanation and more examples, please read the User Guide.