APUE:NDBM database-related library functions

ndbm : Linux/unix the database

< Span style= "Font-family:ar PL UKai cn,serif" >dbm/ndbm:dbm is the old version, ndbm is the new version

gdbm : GNU version

DB : Latest Version

ndbm is a SUS Standard, we take ndbm as an example.

Use ndbm need to install gdbm :

Sudoapt-get Install Libgdbm-dev

include header files: <gdbm-ndbm.h> .

link library: -lgdbm-lgdbm_compat

Use gdbm :

include header files: <gdbm.h>

link library: -lgdbm

#####################################################

#include <gdbm-ndbm.h>

typedefstruct {

Char*dptr;

Intdsize;

}datum;

dbm* Dbm_open (Constchar *filename, int file_open_flags, mode_t file_mode);

database handle returned successfully, error returned NULL .

Open the database, create Filename.pag index files and Filename.dir data files.

void Dbm_close (dbm*database_descriptor);

Close the database and release the resources.

< Span style= "Font-family:ar PL UKai cn,serif" >int dbm_store

store data, return successfully 0 , Failure returns non- 0 .

Store_mode:

Dbm_insert : Add a new record

Dbm_replace : Replace an existing record

Datum Dbm_fetch (Dbm*database_descriptor, Datum key);

gets a record from the database, returns data successfully, fails back NULL .

< Span style= "Font-family:ar PL UKai cn,serif" >int dbm_delete

Delete a record and return successfully 0 , Failure returns non- 0.

Datum Dbm_firstkey (dbm*database_descriptor);

Returns the first record of a database.

Datum Dbm_nextkey (dbm*database_descriptor);

in the call Firstkey after the call, the next record is returned.

int Dbm_error (dbm*database_descriptor);

Returns the error value.

int Dbm_clearerr (dbm*database_descriptor);

Clears the error value.

To be Continued ...

APUE:NDBM database-related library functions