Comparison of the use of fgetgrent () function and fgetpwent () function in C language _c language

C language Fgetgrent () function: Reading group format functions

Header file:

#include <grp.h>  #include <stdio.h>  #include <sys/types.h>

To define a function:

struct Group * getgrent (FILE * stream);

Function Description: Fgetgrent () reads a row of data from the file specified by the parameter stream and returns the data in the group structure. The file specified by the parameter stream must be in the same format as, Etc/group. Group structure definition please refer to getgrent ().

Return value: Returns the group structure data, if returned null indicates no data, or an error occurred.

Example

#include <grp.h>
#include <sys/types.h>
#include <stdio.h>
main ()
{
  struct Group *data;
  FILE *stream;
  int i;
  stream = fopen ("/etc/group", "R");
  while (data = Fgetgrent (stream))!= 0)
  {
    i = 0;
    printf ("%s:%s:%d:", Data->gr_name, DATA->GR_PASSWD, data->gr_gid);
    while (Data->gr_mem[i])
      printf ("%s,", data->gr_mem[i++]);
    printf ("\ n");
  }
  Fclose (stream);
}

Perform:

Root:x:0:root,
bin:x:1:root, bin, daemon
daemon:x:2:root, bin, daemon
sys:x:3:root, bin, Adm
ADM : X:4:root, ADM, daemon
tty:x:5
disk:x:6:root
lp:x:7:daemon, LP
Mem:x:8
kmem:x:9
Wheel:x:10:root
mail:x:12:mail
news:x:13:news
uucp:x:14:uucp
man:x:15
games:x:20
gopher:x:30
dip:x:40:
ftp:x:50
nobody:x:99:

C language Fgetpwent () function: reading password format

Header file:

#include <pwd.h>  #include <stdio.h>  #include <sys/types.h>

To define a function:

struct passwd * fgetpwent (FILE * stream);

Function Description: Fgetpwent () reads a row of data from the file specified by the parameter stream, and then returns the data as a passwd structure. The file specified by the parameter stream must be in the same format as/etc/passwd. passwd structure definition refer to getpwent ().

Return value: Returns the PASSWD structure data, if returned null indicates no data, or an error occurred.

Example

#include <pwd.h>
#include <sys/types.h>
main ()
{
  struct passwd *user;
  FILE *stream;
  stream = fopen ("/etc/passwd", "R");
  while (user = Fgetpwent (stream))!= 0)
  {
    printf ("%s:%d:%d:%s:%s:%s\n", User->pw_name, User->pw_uid, User->pw_gid,
    User->pw_gecos, User->pw_dir, User->pw_shell);
  }

Perform:

Root:0:0:root:/root:/bin/bash
bin:1:1:bin:/bin:
daemon:2:2:daemon:/sbin:
adm:3:4:adm:/var/adm:
LP:4:7:LP:/VAR/SPOOL/LPD:
sync:5:0:sync:/sbin:/bin/sync
shutdown:6:0:shutdown:/sbin:/sbin/ Shutdown
halt:7:0:halt:/sbin:/sbin/halt
mail:8:12:mail:/var/spool/mail:
news:9:13:news:var/spool/ News
UUCP:10:14:UUCP:/VAR/SPOOL/UUCP:
operator:11:0:operator:/root:
games:12:100:games:/usr/ Games:
gopher:13:30:gopher:/usr/lib/gopher-data:
ftp:14:50:ftp user:/home/ftp:
nobody:99:99: nobody:/:
xfs:100:101:x Font Server:/etc/xll/fs:/bin/false
gdm:42:42:/home/gdm:/bin/bash
Kids : 500:500::/home/kids:/bin/bash