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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