Using cmph is quite simple. Take a look in the following examples.
#include <cmph.h>
#include <string.h>
// Create minimal perfect hash function from in-memory vector
int main(int argc, char **argv)
{
// Creating a filled vector
unsigned int i = 0;
const char *vector[] = {"aaaaaaaaaa", "bbbbbbbbbb", "cccccccccc", "dddddddddd", "eeeeeeeeee",
"ffffffffff", "gggggggggg", "hhhhhhhhhh", "iiiiiiiiii", "jjjjjjjjjj"};
unsigned int nkeys = 10;
FILE* mphf_fd = fopen("temp.mph", "w");
// Source of keys
cmph_io_adapter_t *source = cmph_io_vector_adapter((char **)vector, nkeys);
//Create minimal perfect hash function using the brz algorithm.
cmph_config_t *config = cmph_config_new(source);
cmph_config_set_algo(config, CMPH_BRZ);
cmph_config_set_mphf_fd(config, mphf_fd);
cmph_t *hash = cmph_new(config);
cmph_config_destroy(config);
cmph_dump(hash, mphf_fd);
cmph_destroy(hash);
fclose(mphf_fd);
//Find key
mphf_fd = fopen("temp.mph", "r");
hash = cmph_load(mphf_fd);
while (i < nkeys) {
const char *key = vector[i];
unsigned int id = cmph_search(hash, key, (cmph_uint32)strlen(key));
fprintf(stderr, "key:%s -- hash:%u\n", key, id);
i++;
}
//Destroy hash
cmph_destroy(hash);
cmph_io_vector_adapter_destroy(source);
fclose(mphf_fd);
return 0;
}
Download vector_adapter_ex1.c. This example does not work in versions below 0.6.
#include <cmph.h>
#include <string.h>
// Create minimal perfect hash function from in-memory vector
#pragma pack(1)
typedef struct {
cmph_uint32 id;
char key[11];
cmph_uint32 year;
} rec_t;
#pragma pack(0)
int main(int argc, char **argv)
{
// Creating a filled vector
unsigned int i = 0;
rec_t vector[10] = {{1, "aaaaaaaaaa", 1999}, {2, "bbbbbbbbbb", 2000}, {3, "cccccccccc", 2001},
{4, "dddddddddd", 2002}, {5, "eeeeeeeeee", 2003}, {6, "ffffffffff", 2004},
{7, "gggggggggg", 2005}, {8, "hhhhhhhhhh", 2006}, {9, "iiiiiiiiii", 2007},
{10,"jjjjjjjjjj", 2008}};
unsigned int nkeys = 10;
FILE* mphf_fd = fopen("temp_struct_vector.mph", "w");
// Source of keys
cmph_io_adapter_t *source = cmph_io_struct_vector_adapter(vector, (cmph_uint32)sizeof(rec_t), (cmph_uint32)sizeof(cmph_uint32), 11, nkeys);
//Create minimal perfect hash function using the BDZ algorithm.
cmph_config_t *config = cmph_config_new(source);
cmph_config_set_algo(config, CMPH_BDZ);
cmph_config_set_mphf_fd(config, mphf_fd);
cmph_t *hash = cmph_new(config);
cmph_config_destroy(config);
cmph_dump(hash, mphf_fd);
cmph_destroy(hash);
fclose(mphf_fd);
//Find key
mphf_fd = fopen("temp_struct_vector.mph", "r");
hash = cmph_load(mphf_fd);
while (i < nkeys) {
const char *key = vector[i].key;
unsigned int id = cmph_search(hash, key, 11);
fprintf(stderr, "key:%s -- hash:%u\n", key, id);
i++;
}
//Destroy hash
cmph_destroy(hash);
cmph_io_vector_adapter_destroy(source);
fclose(mphf_fd);
return 0;
}
Download struct_vector_adapter_ex3.c. This example does not work in versions below 0.8.
#include <cmph.h>
#include <stdio.h>
#include <string.h>
// Create minimal perfect hash function from in-disk keys using BDZ algorithm
int main(int argc, char **argv)
{
//Open file with newline separated list of keys
FILE * keys_fd = fopen("keys.txt", "r");
cmph_t *hash = NULL;
if (keys_fd == NULL)
{
fprintf(stderr, "File \"keys.txt\" not found\n");
exit(1);
}
// Source of keys
cmph_io_adapter_t *source = cmph_io_nlfile_adapter(keys_fd);
cmph_config_t *config = cmph_config_new(source);
cmph_config_set_algo(config, CMPH_BDZ);
hash = cmph_new(config);
cmph_config_destroy(config);
//Find key
const char *key = "jjjjjjjjjj";
unsigned int id = cmph_search(hash, key, (cmph_uint32)strlen(key));
fprintf(stderr, "Id:%u\n", id);
//Destroy hash
cmph_destroy(hash);
cmph_io_nlfile_adapter_destroy(source);
fclose(keys_fd);
return 0;
}
Download file_adapter_ex2.c and keys.txt. This example does not work in versions below 0.8.
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Enjoy!