CMPH - Examples

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
  	const char *vector[] = {"aaaaaaaaaa", "bbbbbbbbbb", "cccccccccc", "dddddddddd", "eeeeeeeeee",
  				"ffffffffff", "gggggggggg", "hhhhhhhhhh", "iiiiiiiiii", "jjjjjjjjjj"};
  	unsigned int nkeys = 10;
  	// Source of keys
  	cmph_io_adapter_t *source = cmph_io_vector_adapter((char **)vector, nkeys);
  	
  	//Create minimal perfect hash function using the default (chm) algorithm.
  	cmph_config_t *config = cmph_config_new(source);
  	cmph_t *hash = cmph_new(config);
  	cmph_config_destroy(config);
  	
  	//Find key
  	const char *key = "jjjjjjjjjj";
  	unsigned int id = cmph_search(hash, key, strlen(key));
  	fprintf(stderr, "Id:%u\n", id);
  	//Destroy hash
  	cmph_destroy(hash);
  	cmph_io_vector_adapter_destroy(source);
  	return 0;
  }

Download vector_adapter_ex1.c. This example does not work in versions below 0.3.

  #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, sizeof(rec_t), sizeof(cmph_uint32), 11, nkeys); 
  
      //Create minimal perfect hash function using the default (chm) 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 0.7.

  #include <cmph.h>
  #include <stdio.h>
  #include <string.h>
   // Create minimal perfect hash function from in-disk keys using BMZ 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_BMZ);
  	hash = cmph_new(config);
  	cmph_config_destroy(config);
  	
  	//Find key
  	const char *key = "jjjjjjjjjj";
  	unsigned int id = cmph_search(hash, key, 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

Enjoy!

Fabiano Cupertino Botelho