|Important||This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer|
int isalnum( int c ); int iswalnum( wint_t c );
Each of these routines returns nonzero if c is a particular representation of an alphanumeric character.
- Integer to test.
isalnum returns a non-zero value if either isalpha or isdigit is nonzero for c, that is, if c is within the ranges A – Z, a – z, or 0 – 9. iswalnum returns a non-zero value if either iswalpha or iswdigit is nonzero for c. Each of these routines returns 0 if c does not satisfy the test condition.
The result of the test condition for the isalnum function depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. For iswalnum, the result of the test condition is independent of locale.
When used with a debug CRT library, isalnum will display a CRT assert if passed a parameter that isn't EOF or in the range of 0 through 0xFF. When used with a debug CRT library, isalnum will use the parameter as an index into an array, with undefined results if the parameter isn't EOF or in the range of 0 through 0xFF.
Generic-Text Routine Mappings
|TCHAR.H routine||_UNICODE & _MBCS not defined||_MBCS defined||_UNICODE defined|
|isalnum||<ctype.h>||ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP|
|iswalnum||<ctype.h> or <wchar.h>||ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP|
For additional compatibility information, see Compatibility in the Introduction.
All versions of the C run-time libraries.