a example code for gdbm using

dbm.c

/* db_add.c: storing
   written by rock <shirock@residence.educities.edu.tw>, 1999.11.29
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <gdbm.h>

#define datum_set(um, buf) { um.dptr = buf; um.dsize = strlen(buf); }

int db_ls(char *dbname) {
	GDBM_FILE dbf;
	datum key, next, data;
	int n = 1;

	dbf = gdbm_open(dbname, 0, GDBM_READER, 0, NULL);
	if(!dbf) {
		printf("%s\n", gdbm_strerror(gdbm_errno));
		return 1;
	}
	key = gdbm_firstkey(dbf);
	while( key.dptr ) {
		data = gdbm_fetch(dbf, key);
		printf("(%d) %s:\t%s\n", n++, key.dptr, data.dptr);
		next = gdbm_nextkey(dbf, key);
		free(key.dptr);
		key = next;
	}
	gdbm_close(dbf);
	return 0;
}

int db_rm(char *dbname)
{
	GDBM_FILE dbf;
	char keyb[256];
	datum key;

	dbf = gdbm_open(dbname, 0, GDBM_WRITER, 0, NULL);
	if( !dbf ) {
		printf("%s\n", gdbm_strerror(gdbm_errno));
		return 1;
	}
	puts("Input key: ");
	gets(keyb);

	key.dptr = keyb; key.dsize = strlen(keyb);
	if(gdbm_delete(dbf, key)) {
		printf("%s\n", gdbm_strerror(gdbm_errno));
		gdbm_close(dbf);
		return 1;
	}
	puts("Removing record successed\n");
	gdbm_close(dbf);
	return 0;
}

int db_add(char *dbname) {
	char keyb[256], datab[256];
	GDBM_FILE dbf;
	datum key, data;

	if( !(dbf = gdbm_open(dbname, 0, GDBM_WRCREAT, 0644, NULL)) ) {
		printf("%s\n", gdbm_strerror(gdbm_errno));
		return 1;
	}

	puts("Input key: ");
	gets(keyb);
	puts("Input data: ");
	gets(datab);

	datum_set(key, keyb);
	datum_set(data, datab);

	if( gdbm_store(dbf, key, data, GDBM_INSERT) ) {
		printf("%s\nRecord may be exist.\n", gdbm_strerror(gdbm_errno));
		gdbm_close(dbf);
		return 1;
	}
	puts("Storing record successed.\n");
	gdbm_close(dbf);
	return 0;
}


int main(int argc, char *argv[]) {
	char keyb[256], datab[256], *dbname;
	GDBM_FILE dbf;
	datum key, data;

	if( argc < 3) {
		printf("Usage: %s add/ls/rm <dbname>\n", argv[0]);
		return 1;
	}
	if (!strcmp(argv[1], "add")){
		db_add(argv[2]);
	} else if (!strcmp(argv[1], "ls")){
		db_ls(argv[2]);
	} else if (!strcmp(argv[1], "rm")){
		db_rm(argv[2]);
	}

	return 0;
}