Seth Woolley's Man Viewer

ISALPHA(3)                 Linux Programmer's Manual                ISALPHA(3)



NAME
       isalnum, isalpha, isascii, isblank, 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 isascii(int c);
       int isblank(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 (isal-
              pha(c) || isdigit(c)).

       isalpha()
              checks for an alphabetic character; in(1,8) the standard "C"  locale(3,5,7),
              it  is  equivalent  to  (isupper(c)  ||  islower(c)).   In  some
              locales, there may be additional characters for which  isalpha()
              is true--letters which are neither upper case nor lower case.

       isascii()
              checks  whether  c is a 7-bit unsigned char value that fits into
              the ASCII character set.  This function is a BSD  extension  and
              is also an SVID extension.

       isblank()
              checks for a blank character; that is, a space or a tab.

       iscntrl()
              checks for a control character.

       isdigit()
              checks for a digit (0 through 9).

       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
              a b c d e f A B C D E F.

RETURN VALUE
       The values returned are nonzero if(3,n)  the  character  c  falls  into  the
       tested class, and a zero value if(3,n) not.

CONFORMING TO
       ANSI  -  C,  BSD 4.3.  isascii() is a BSD extension and is also an SVID
       extension.  isblank() conforms to ISO C99 7.4.1.3.

NOTE
       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(1,8) the default C locale.

SEE ALSO
       setlocale(3), tolower(3), toupper(3), ascii(1,7)(7), locale(3,5,7)(7)



GNU                               1995-09-02                        ISALPHA(3)