isalnum
[alphanumeric character predicate]
SYNOPSIS
#include
<ctype.h>
int isalnum(int
c);
DESCRIPTION
isalnum
is a macro which classifies ASCII integer
values by table lookup. It is a predicate returning non-zero for alphabetic
or numeric ASCII characters, and 0
for other arguments. It is defined
for all integer values.
You can use a compiled subroutine instead of the macro definition by undefining the macro, using #undef isalnum.
RETURNS
isalnum
returns non-zero if c
is a letter (a–z
or A–Z)
or a digit (0–9).
COMPLIANCE
isalnum
is ANSI C.
No OS subroutines are required.
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