Syntax

#include <wctype.h>
                                      /* test for:     */
int iswalnum(wint_t wc);  /* wide alphanumeric character */
int iswalpha(wint_t wc);  /* wide alphabetic character   */
int iswcntrl(wint_t wc);  /* wide control character      */
int iswdigit(wint_t wc);  /* wide decimal digit          */
int iswgraph(wint_t wc);  /* wide printable character, excluding space */
int iswlower(wint_t wc);  /* wide lowercase character    */
int iswprint(wint_t wc);  /* wide printable character, including space */
int iswpunct(wint_t wc);  /* wide punctuation character, excluding space */
int iswspace(wint_t wc);  /* wide whitespace character   */
int iswupper(wint_t wc);  /* wide uppercase character    */
int iswxdigit(wint_t wc); /* wide hexadecimal digit      */

These functions test a given wide integer value wc to determine whether it has a certain property as defined by the LC_CTYPE category of your current locale. The value of wc must be representable as a wchar_t or WEOF.

The functions test for the following:

iswalnum

Wide alphanumeric character (uppercase or lowercase letter, or decimal digit), as defined in the locale source file in the alnum class of the LC_CTYPE category of the current locale.
iswalpha
Wide alphabetic character, as defined in the locale source file in the alpha class of the LC_CTYPE category of the current locale.
iswcntrl
Wide control character, as defined in the locale source file in the cntrl class of the LC_CTYPE category of the current locale.
iswdigit
Wide decimal digit (0 through 9), as defined in the locale source file in the digit class of the LC_CTYPE category of the current locale.
iswgraph
Wide printable character, excluding the space character, as defined in the locale source file in the graph class of the LC_CTYPE category of the current locale.
iswlower
Wide lowercase letter, as defined in the locale source file in the lower class of the LC_CTYPE category of the current locale.
iswprint
Wide printable character, including the space character, as defined in the locale source file in the print class of the LC_CTYPE category of the current locale.
iswpunct
Wide non-alphanumeric printable character, excluding the space character, as defined in the locale source file in the punct class of the LC_CTYPE category of the current locale.
iswspace
Wide white-space character, as defined in the locale source file in the space class of the LC_CTYPE category of the current locale.
iswupper
Wide uppercase letter, as defined in the locale source file in the upper class of the LC_CTYPE category of the current locale.
iswxdigit
Wide hexadecimal digit (0 through 9, a through f, or A through F), as defined in the locale source file in the xdigit class of the LC_CTYPE category of the current locale.
You can redefine any character class in the LC_CTYPE category of the current locale. For more information, see "Introduction to Locales" in the VisualAge C++ Programming Guide.

These functions return a nonzero value if the wide integer satisfies the test value; 0 if it does not.

This example analyzes all characters between 0x0 and 0xFF. The output of this example is a 256-line table showing the characters from 0 to 255 and indicates if the characters have the properties tested for.

#include <locale.h>#include <stdio.h>
#include <wctype.h>

#define UPPER_LIMIT   0xFF

int main(void)
{
   wint_t wc;

   setlocale(LC_ALL, "En_US");

   for (wc = 0; wc <= UPPER_LIMIT; wc++) {
      printf("%#4x ", wc);
      printf("%lc", iswprint(wc) ? (wchar_t)wc    : " ");
      printf("%s", iswalnum(wc)  ? " AN" : "   ");
      printf("%s", iswalpha(wc)  ? " A " : "   ");
      printf("%s", iswcntrl(wc)  ? " C " : "   ");
      printf("%s", iswdigit(wc)  ? " D " : "   ");
      printf("%s", iswgraph(wc)  ? " G " : "   ");
      printf("%s", iswlower(wc)  ? " L " : "   ");
      printf("%s", iswpunct(wc)  ? " PU" : "   ");
      printf("%s", iswspace(wc)  ? " S " : "   ");
      printf("%s", iswprint(wc)  ? " PR" : "   ");
      printf("%s", iswupper(wc)  ? " U " : "   ");
      printf("%s", iswxdigit(wc) ? " H " : "   ");
      putchar('\n');
   }
   return 0;

   /****************************************************************************
      The output should be similar to :
      :
      0x20                        S  PR
      0x21 !             G     PU    PR
      0x22 "             G     PU    PR
      0x23 #             G     PU    PR
      0x24 $             G     PU    PR
      0x25 %             G     PU    PR
      0x26 &             G     PU    PR
      0x27 '             G     PU    PR
      0x28 (             G     PU    PR
      0x29 )             G     PU    PR
      0x2a *             G     PU    PR
      0x2b +             G     PU    PR
      0x2c ,             G     PU    PR
      0x2d -             G     PU    PR
      0x2e .             G     PU    PR
      0x2f /             G     PU    PR
      0x30 0 AN       D  G           PR    H
      0x31 1 AN       D  G           PR    H
      0x32 2 AN       D  G           PR    H
      0x33 3 AN       D  G           PR    H
      0x34 4 AN       D  G           PR    H
      0x35 5 AN       D  G           PR    H
      0x36 6 AN       D  G           PR    H
      0x37 7 AN       D  G           PR    H
      0x38 8 AN       D  G           PR    H
      0x39 9 AN       D  G           PR    H
      :
   ****************************************************************************/
}

• isalnum to isxdigit
  
• isascii
  
• iswctype

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