C Standard Library

C <wctype.h> - iswalnum() Function

The C <wctype.h> iswalnum() function is used to check if the given wide character is an alphanumeric letter. An alphanumeric letter is either a decimal digit or an uppercase or lowercase letter. In the default "C" locale, an alphanumeric letter is a letter for which either iswdigit() or iswupper() or iswlower() function returns true. Other locales may consider a different selection of wide characters as alphanumeric letters.


int iswalnum ( wint_t ch );               


ch Specify the wide character to be checked, casted to an wint_t, or WEOF.

Return Value

Returns non-zero value (i.e, true) if ch is an alphanumeric letter, else returns zero (i.e, false).


The example below shows the usage of iswalnum() function.

#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
int main (){
  wchar_t str[50] = L"98Hi@@";

  //counting the numbers of 
  //alphanumeric letters in str
  int i = 0, count = 0;
  while(str[i]) {

  //displaying the output
  printf("%ls contains %d alphanumeric letters.", str, count); 
  return 0;

The output of the above code will be:

98Hi@@ contains 4 alphanumeric letters.

❮ C <wctype.h> Library