Name
isalnum
Synopsis
Ascertains whether a given character is alphanumeric
#include <ctype.h> intisalnum
( intc
);
The function isalnum()
tests whether its character argument is alphanumeric; that is,
whether the character is either a letter of the alphabet or a digit.
In other words, isalnum()
is true
for all characters for which either isalpha()
or isdigit()
is true.
Which characters are considered alphabetic or numeric depends
on the current locale setting for the localization category LC_CTYPE
, which you can query or change
using the setlocale()
function.
If the character is alphanumeric, isalnum()
returns a nonzero value (that
is, true
); if not, the function
returns 0 (false
).
Example
See the example for isprint()
in this
chapter.
See Also
isalpha()
, isblank()
, iscntrl()
, isdigit()
, isgraph()
, islower()
, isprint()
, ispunct()
, isspace()
, isupper()
, isxdigit()
; the
corresponding C99 function for wide characters, iswalnum()
; setlocale()
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