不能编译gdbm程序？(解决)

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本文介绍了在Ubuntu 10.04中编译gdbm程序时遇到的问题及解决方案。编译时由于缺少gdbm库，需要从GNU网站下载并安装，同时注意安装ndbm。在尝试编译时遇到undefined reference错误，通过添加`-lgdbm`和`-lgdbm_compat`链接选项成功解决。

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下面是一个从《Beginning Linux Programming 3rd》中的一个例子程序，但是在Ubuntu下编译不了，原因是10.04中没有安装gdbm，在www.gnu.org上下载gdbm，安装时要记得将make install_compa，即将ndbm同时安装上。

#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <fcntl.h> #include <ndbm.h> #include <string.h> #define TEST_DB_FILE "/tmp/dbm1_test" #define ITEMS_USED 3 /* A struct to use to test dbm */ struct test_data { char misc_chars[15]; int any_integer; char more_chars[21]; }; int main() { struct test_data items_to_store[ITEMS_USED]; struct test_data item_retrieved; char key_to_use[20]; int i, result; datum key_datum; datum data_datum; DBM *dbm_ptr; dbm_ptr = dbm_open(TEST_DB_FILE, O_RDWR | O_CREAT, 0666); if (!dbm_ptr) { fprintf(stderr, "Failed to open database/n"); exit(EXIT_FAILURE); } /* put some data in the structures */ memset(items_to_store, '/0', sizeof(items_to_store)); strcpy(items_to_store[0].misc_chars, "First!"); items_to_store[0].any_integer = 47; strcpy(items_to_store[0].more_chars, "foo"); strcpy(items_to_store[1].misc_chars, "bar"); items_to_store[1].any_integer = 13; strcpy(items_to_store[1].more_chars, "unlucky?"); strcpy(items_to_store[2].misc_chars, "Third"); items_to_store[2].any_integer = 3; strcpy(items_to_store[2].more_chars, "baz"); for (i = 0; i < ITEMS_USED; i++) { /* build a key to use */ sprintf(key_to_use, "%c%c%d", items_to_store[i].misc_chars[0], items_to_store[i].more_chars[0], items_to_store[i].any_integer); /* build the key datum strcture */ key_datum.dptr = (void *)key_to_use; key_datum.dsize = strlen(key_to_use); data_datum.dptr = (void *)&items_to_store[i]; data_datum.dsize = sizeof(struct test_data); result = dbm_store(dbm_ptr, key_datum, data_datum, DBM_REPLACE); if (result != 0) { fprintf(stderr, "dbm_store failed on key %s/n", key_to_use); exit(2); } } /* for */ /* now try and retrieve some data */ sprintf(key_to_use, "bu%d", 13); /* this is the key for the second item */ key_datum.dptr = key_to_use; key_datum.dsize = strlen(key_to_use); data_datum = dbm_fetch(dbm_ptr, key_datum); if (data_datum.dptr) { printf("Data retrieved/n"); memcpy(&item_retrieved, data_datum.dptr, data_datum.dsize); printf("Retrieved item - %s %d %s/n", item_retrieved.misc_chars, item_retrieved.any_integer, item_retrieved.more_chars); } else { printf("No data found for key %s/n", key_to_use); } dbm_close(dbm_ptr); exit(EXIT_SUCCESS); }

尝试编译1：
$gcc dbm1.c -o gdbm1 -lgdbm
错误信息：
/tmp/cc2vMknU.o: In function `main':
dbm1.c: (.text+0x2d): undefined reference to `dbm_open'
dbm1.c: (.text+0x244): undefined reference to `dbm_store'
dbm1.c: (.text+0x2ee): undefined reference to `dbm_fetch'
dbm1.c: (.text+0x379): undefined reference to `dbm_close'
collect2: ld returned 1 exit status

尝试编译2：
$ gcc dbm1.c -o gdbm1 -lndbm -L/usr/lib
错误信息：
/usr/bin/ld: cannot find -lndbm
collect2: ld returned 1 exit status

解决了：
如果用gdbm，还要兼容dbm或ndmb，编译的时候要连接上gdbm_compat：
$ gcc dbm1.c -o dbm1 -lgdbm -lgdbm_compat