is

Algorithms for Image Processing and Computer Vision Source Code

@c ----------------------------------------------------------------------
@node isalnum, ctype
@heading @code{isalnum}
@subheading Syntax

@example
#include <ctype.h>

int isalnum(int c);
@end example

@subheading Description

Tells if @var{c} is any letter or digit.

@subheading Return Value

Nonzero if @var{c} is a letter or digit, else zero.

@subheading Example

@c ----------------------------------------------------------------------
@node isalpha, ctype
@heading @code{isalpha}
@subheading Syntax

@example
#include <ctype.h>

int isalpha(int c);
@end example

@subheading Description

Tells if @var{c} is a letter.

@subheading Return Value

Nonzero if @var{c} is a letter, else zero.

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

@example
#include <osfcn.h>

int isatty(int fd);
@end example

@subheading Description

Tells if the file descriptor refers to a physical device or a disk file.

@subheading Return Value

Nonzero if @var{fd} is a device, zero if it is a disk file.

@subheading Example

@example
if (isatty(1))
  fflush(stdout);
@end example

@c ----------------------------------------------------------------------
@node iscntrl, ctype
@heading @code{iscntrl}
@subheading Syntax

@example
#include <ctype.h>

int iscntrl(int c);
@end example

@subheading Description

Tells if @var{c} is a control character.

@subheading Return Value

Nonzero if @var{c} is a control character, else zero.

@c ----------------------------------------------------------------------
@node isdigit, ctype
@heading @code{isdigit}
@subheading Syntax

@example
#include <ctype.h>

int isdigit(int c);
@end example

@subheading Description

Tells if @var{c} is a digit.

@subheading Return Value

Nonzero if @var{c} is a digit, else zero.

@c ----------------------------------------------------------------------
@node isgraph, ctype
@heading @code{isgraph}
@subheading Syntax

@example
#include <ctype.h>

int isgraph(int c);
@end example

@subheading Description

Tells if @var{c} is a visible printing character.  Space is not
included. 

@subheading Return Value

Nonzero if @var{c} is a visible printing character, else zero.

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

@example
#include <tzfile.h>

int isleap(int year);
@end example

@subheading Description

This function determines if the given year is a leap year.

@subheading Return Value

True if it is a leap year, else false.

@subheading Example

@example
if (isleap(year))
  printf("Feb 29");
@end example

@c ----------------------------------------------------------------------
@node islower, ctype
@heading @code{islower}
@subheading Syntax

@example
#include <ctype.h>

int islower(int c);
@end example

@subheading Description

Tells if @var{c} is lower case or not.

@subheading Return Value

Nonzero if @var{c} is lower case, else zero.

@c ----------------------------------------------------------------------
@node isprint, ctype
@heading @code{isprint}
@subheading Syntax

@example
#include <ctype.h>

int isprint(int c);
@end example

@subheading Description

Tells if @var{c} is a printing character, which includes the space
character.

@subheading Return Value

Nonzero if @var{c} is a printing character, else zero.

@c ----------------------------------------------------------------------
@node ispunct, ctype
@heading @code{ispunct}
@subheading Syntax

@example
#include <ctype.h>

int ispunct(int c);
@end example

@subheading Description

Tells if @var{c} is any printing character except space and those
indicated by @code{isalnum}. 

@subheading Return Value

Nonzero if @var{c} is punctuation, else zero.

@c ----------------------------------------------------------------------
@node isspace, ctype
@heading @code{isspace}
@subheading Syntax

@example
#include <ctype.h>

int isspace(int c);
@end example

@subheading Description

Tells if @var{c} is whitespace, that is, carriage return, newline, form
feed, tab, vertical tab, or space.

@subheading Return Value

Nonzero if @var{c} is whitespace, else zero.

@c ----------------------------------------------------------------------
@node isupper, ctype
@heading @code{isupper}
@subheading Syntax

@example
#include <ctype.h>

int isupper(int c);
@end example

@subheading Description

Tells if @var{c} is an upper case character or not.

@subheading Return Value

Nonzero if @var{c} is upper case, else zero.

@c ----------------------------------------------------------------------
@node isxdigit, ctype
@heading @code{isxdigit}
@subheading Syntax

@example
#include <ctype.h>

int isxdigit(int c);
@end example

@subheading Description

Tells if @var{c} is a valid hexidecimal digit or not.  This includes
@code{[0-9a-fA-f]}. 

@subheading Return Value

Nonzero if @var{c} is a hex digit, else zero.