# 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
          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!

Davi de Castro Reis

Djamel Belazzougui

Fabiano Cupertino Botelho

Nivio Ziviani