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#include <stdio.h> /* gets */
#include <stdlib.h> /* atoi, malloc */
#include <string.h> /* strcpy */
#include "uthash.h"
struct my_struct {
int id; /* key */
char name[10];
UT_hash_handle hh; /* makes this structure hashable */
};
struct my_struct *users = NULL;
void add_user(int user_id, char *name)
{
struct my_struct *s;
HASH_FIND_INT(users, &user_id, s); /* id already in the hash? */
if (s == NULL) {
s = (struct my_struct*)malloc(sizeof(struct my_struct));
s->id = user_id;
HASH_ADD_INT(users, id, s); /* id: name of key field */
}
strcpy(s->name, name);
}
struct my_struct *find_user(int user_id)
{
struct my_struct *s;
HASH_FIND_INT(users, &user_id, s); /* s: output pointer */
return s;
}
void delete_user(struct my_struct *user)
{
HASH_DEL(users, user); /* user: pointer to deletee */
free(user);
}
void delete_all()
{
struct my_struct *current_user, *tmp;
HASH_ITER(hh, users, current_user, tmp) {
HASH_DEL(users, current_user); /* delete it (users advances to next) */
free(current_user); /* free it */
}
}
void print_users()
{
struct my_struct *s;
for (s = users; s != NULL; s = (struct my_struct*)(s->hh.next)) {
printf("user id %d: name %s\n", s->id, s->name);
}
}
int name_sort(struct my_struct *a, struct my_struct *b)
{
return strcmp(a->name, b->name);
}
int id_sort(struct my_struct *a, struct my_struct *b)
{
return (a->id - b->id);
}
void sort_by_name()
{
HASH_SORT(users, name_sort);
}
void sort_by_id()
{
HASH_SORT(users, id_sort);
}
int main()
{
char in[10];
int id = 1, running = 1;
struct my_struct *s;
unsigned num_users;
while (running) {
printf(" 1. add user\n");
printf(" 2. add/rename user by id\n");
printf(" 3. find user\n");
printf(" 4. delete user\n");
printf(" 5. delete all users\n");
printf(" 6. sort items by name\n");
printf(" 7. sort items by id\n");
printf(" 8. print users\n");
printf(" 9. count users\n");
printf("10. quit\n");
gets(in);
switch(atoi(in)) {
case 1:
printf("name?\n");
add_user(id++, gets(in));
break;
case 2:
printf("id?\n");
gets(in);
id = atoi(in);
printf("name?\n");
add_user(id, gets(in));
break;
case 3:
printf("id?\n");
s = find_user(atoi(gets(in)));
printf("user: %s\n", s ? s->name : "unknown");
break;
case 4:
printf("id?\n");
s = find_user(atoi(gets(in)));
if (s) {
delete_user(s);
} else {
printf("id unknown\n");
}
break;
case 5:
delete_all();
break;
case 6:
sort_by_name();
break;
case 7:
sort_by_id();
break;
case 8:
print_users();
break;
case 9:
num_users = HASH_COUNT(users);
printf("there are %u users\n", num_users);
break;
case 10:
running = 0;
break;
}
}
delete_all(); /* free any structures */
return 0;
}
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