ISALPHA

Section: Linux Programmer's Manual (3)
Updated: April 4, 1993
Index Return to Main Contents
 

NAME

isalnum, isalpha, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classification routines  

SYNOPSIS

#include <ctype.h>

int isalnum (int c);
int isalpha (int c);
int iscntrl (int c);
int isdigit (int c);
int isgraph (int c);
int islower (int c);
int isprint (int c);
int ispunct (int c);
int isspace (int c);
int isupper (int c);
int isxdigit (int c);
 

DESCRIPTION

These functions check whether c, which must have the value of an unsigned char or EOF, falls into a certain character class according to the current locale.
isalnum()
checks for an alphanumeric character; it is equivalent to (isalpha(c) || isdigit(c)).
isalpha()
checks for an alphabetic character; it is equivalent to (isupper(c) || islower(c)).
iscntrl()
checks for a control character.
isdigit()
checks for a digit.
isgraph()
checks for any printable character except space.
islower()
checks for a lower - case character.
isprint()
checks for any printable character including space.
ispunct()
checks for any printable character which is not a space or an alphanumeric character.
isspace()
checks for white - space characters. In the C and POSIX locales, these are: space, form-feed ('\f'), newline ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v').
isupper()
checks for an uppercase letter.
isxdigit()
checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5 6 7 8 9 0 a b c d e f A B C D E F
 

RETURN VALUE

The values returned are nonzero if the character c falls into the tested class, and a zero value if not.  

CONFORMS TO

ANSI - C, BSD 4.3  

BUGS

The details of what characters belong into which class depend on the current locale. For example, isupper() will not recognize an A - umlaut as an uppercase letter in the default C locale.  

SEE ALSO

toupper(3), setlocale(3), ascii(7), locale(7)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
CONFORMS TO
BUGS
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 12:23:43 GMT, March 22, 2025