ge

Algorithms for Image Processing and Computer Vision Source Code

@c ----------------------------------------------------------------------
@node _get_default_drive, dos
@heading @code{_get_default_drive}
@subheading Syntax

@example
int _get_default_drive(void);
@end example

@subheading Description

Gets the default drive.

@subheading Return Value

0 for drive A:, 1 for drive B:, etc, up to 26 for Z:

@subheading Example

@example
printf("Current drive is %c:\n", _get_current_drive()+'a');
@end example

@c ----------------------------------------------------------------------
@node getc, stdio
@heading @code{getc}
@subheading Syntax

@example
#include <stdio.h>

int getc(FILE *file);
@end example

@subheading Description

Get one character from @var{file}.

@subheading Return Value

The character ([0..255]) or @code{EOF} if eof or error.

@subheading Example

@example
int c;
while ((c=getc(stdin)) != EOF)
  putc(c, stdout);
@end example

@c ----------------------------------------------------------------------
@node getcbrk, dos
@heading @code{getcbrk}
@subheading Syntax

@example
#include <dos.h>

int getcbrk(void);
@end example

@subheading Description

Get the setting of the Ctrl-C checking flag in MS-DOS.

@xref{setcbrk}

@subheading Return Value

0 if not checking, 1 if checking.

@c ----------------------------------------------------------------------
@node getchar, stdio
@heading @code{getchar}
@subheading Syntax

@example
#include <stdio.h>

int getchar(void);
@end example

@subheading Description

The same as @code{fgetc(stdin)} (@pxref{fgetc}).

@subheading Return Value

The character, or @code{EOF}.

@c ----------------------------------------------------------------------
@node getcwd, file system
@heading @code{getcwd}
@subheading Syntax

@example
#include <osfcn.h>

char *getcwd(char *buffer, int max);
@end example

@subheading Description

Get the current directory.  The return value includes the drive
specifier.  If @var{buffer} is @code{NULL}, a buffer of size @var{max}
is allocated.  This call fails if more than @var{max} characters are
required to specify the current directory. 

If @code{getcwd} allocates a buffer for you, you may later free is with
@code{free}. 

@subheading Return Value

The buffer, either @var{buffer} or a newly-allocated buffer, or
@code{NULL} on error. 

@subheading Example

@example
char *buf = getcwd(0, PATH_MAX);
printf("cwd is %s\n", buf);
free(buf);
@end example

@c ----------------------------------------------------------------------
@node getdate, time
@heading @code{getdate}
@subheading Syntax

@example
#include <dos.h>

void getdate(struct date *);
@end example

@subheading Description

This function gets the current date.  The return structure is as follows:

@example
struct date @{
  short da_year;
  char  da_day;
  char  da_mon;
@};
@end example

@xref{setdate} @xref{gettime}

@subheading Return Value

None.

@subheading Example

@example
struct date d;
getdate(&d);
@end example

@c ----------------------------------------------------------------------
@node getdfree, file system
@heading @code{getdfree}
@subheading Syntax

@example
#include <dos.h>

void getdfree(unsigned char drive, struct dfree *ptr);
@end example

@subheading Description

This function gets information about the size and fullness of the given
drive (0=default, 1=A:, etc).  The return structure is as follows:

@example
struct dfree @{
  unsigned df_avail; /* number of available clusters */
  unsigned df_total; /* total number of clusters */
  unsigned df_bsec;  /* bytes per sector */
  unsigned df_sclus; /* sectors per cluster */
@};
@end example

@subheading Return Value

None.

@subheading Example

@example
struct dfree d;
getdfree(3, &d); /* drive C: */
@end example

@c ----------------------------------------------------------------------
@node getdisk, dos
@heading @code{getdisk}
@subheading Syntax

@example
#include <dir.h

int getdisk(void);
@end example

@subheading Description

Gets the current disk (0=A).

@xref{setdisk}

@subheading Return Value

The current disk.

@subheading Example

@example
printf("This drive is %c:\n", getdisk() + 'A');
@end example

@c ----------------------------------------------------------------------
@node getdtablesize, posix
@heading @code{getdtablesize}
@subheading Syntax

@example
#include <osfcn.h>

int getdtablesize(void);
@end example

@subheading Description

Get the maximum number of open file descriptors the system supports. 
Should depend on the setting of @code{FILES=} in @file{config.sys}, but
is currently hardcoded to 50. 

@subheading Return Value

The number of file descriptors.

@c ----------------------------------------------------------------------
@node getegid, unix
@heading @code{getegid}
@subheading Syntax

@example
#include <osfcn.h>

int getegid(void);
@end example

@subheading Description

Get the effective group id.

@subheading Return Value

42

@c ----------------------------------------------------------------------
@node getenv, environment
@heading @code{getenv}
@subheading Syntax

@example
#include <stdlib.h>

char *getenv(const char *name);
@end example

@subheading Description

Get the setting of the environment variable @var{name}.  Do not alter or
free the returned value. 

@subheading Return Value

The value, or @code{NULL} if that variable does not exist.

@subheading Example

@example
char *term = getenv("TERM");
@end example

@c ----------------------------------------------------------------------
@node geteuid, unix
@heading @code{geteuid}
@subheading Syntax

@example
#include <osfcn.h>

int geteuid(void);
@end example

@subheading Description

Gets the effective UID.

@subheading Return Value

42

@c ----------------------------------------------------------------------
@node getftime, file system
@heading @code{getftime}
@subheading Syntax

@example
#include <dos.h>

int getftime(int handle, struct ftime *ptr);
@end example

@subheading Description

Get the timestamp for the given file handle.  The return structure is as
follows:

@example
struct ftime @{
  unsigned ft_tsec:5;	/* 0-29, double to get real seconds */
  unsigned ft_min:6;	/* 0-59 */
  unsigned ft_hour:5;	/* 0-23 */
  unsigned ft_day:5;	/* 1-31 */
  unsigned ft_month:4;	/* 1-12 */
  unsigned ft_year:7;	/* since 1980 */
@}
@end example

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Example

@example
struct ftime t;
getftime(fd, &t);
@end example

@c ----------------------------------------------------------------------
@node getgid, unix
@heading @code{getgid}
@subheading Syntax

@example
#include <osfcn.h>

int getgid(void);
@end example

@subheading Description

Get the current group id.

@subheading Return Value

42

@c ----------------------------------------------------------------------
@node getgrent, unix
@heading @code{getgrent}
@subheading Syntax

@example
#include <grp.h>

struct group *getgrent(void);
@end example

@subheading Description

This function returns the next available group entry.  Note that for
MS-DOS, this is simulated.  If the environment variable GROUP is set,
that is the name of the only group returned, else the only group is
"other". 

The return type of this and related function is as follows:

@example
struct group @{
  char *  gr_name;   /* "other" or getenv("GROUP"); */
  char *  gr_passwd; /* "*" */
  int     gr_gid;    /* result of getgid() */
  char ** gr_mem;    /* always empty */
@};
@end example

@subheading Return Value

The next structure, or @code{NULL} at the end of the list.

@subheading Example

@example

struct group *g;
setgrent();
while ((g = getgrent()) != NULL)
@{
  printf("group %s gid %d\n", g->gr_name, g->gr_gid);
@}
endgrent();
@end example

@c ----------------------------------------------------------------------
@node getgrgid, unix
@heading @code{getgrgid}
@subheading Syntax

@example
#include <grp.h>

extern struct group *getgrgid(int gid);
@end example

@subheading Description

This function returns the group entry that matches @var{gid}. 
@xref{getgrent}

@subheading Return Value

The matching group, or @code{NULL} if none match.

@c ----------------------------------------------------------------------
@node getgrnam, unix
@heading @code{getgrnam}
@subheading Syntax

@example
#include <grp.h>

struct group *getgrnam(char *name);
@end example

@subheading Description

This function returns the group entry for the group named @var{name}. 
@xref{getgrent}

@subheading Return Value

The matching group, or @code{NULL} if none match.

@c ----------------------------------------------------------------------
@node getgroups, unix
@heading @code{getgroups}

@subheading Description

This function is provided only to assist in porting from Unix.  It
always returns an error condition. 

@c ----------------------------------------------------------------------
@node getkey, dos
@heading @code{getkey}
@subheading Syntax

@example
#include <pc.h>
#include <keys.h>

int getkey(void);
@end example

@subheading Description

Waits for the user to press one key, then returns that key.  Alt-key
combinations have 0x100 added to them.  Extended keys return their
non-extended codes. 

The file @file{keys.h} has symbolic names for many of the keys.

@xref{getxkey}

@subheading Return Value

The key pressed.

@subheading Example

@example
while (getkey() != K_Alt_3)
  do_something();
@end example

@c ----------------------------------------------------------------------
@node getlogin, unix
@heading @code{getlogin}
@subheading Syntax

@example
#include <unistd.h>

char *getlogin(void);
@end example

@subheading Description

Get the login ID of the user.

@subheading Return Value

Returns the value of the @code{USER} environment variable, else the
@code{LOGNAME} environment variable, else @code{"dosuser"}. 

@subheading Example

@example
printf("I am %s\n", getlogin());
@end example

@c ----------------------------------------------------------------------
@node getlongpass, unix
@heading @code{getlongpass}
@subheading Syntax

@example
int getlongpass(const char *prompt, char *password, int max_length);
@end example

@subheading Description

Read a password from the user.  First, the prompt is sent to