.TH isalnum() "" "" "ctype Function (libc)"
.PC "Check if a character is a number or letter"
\fB#include <ctype.h>\fR
\fBint isalnum(\fIc\^\fB) int \fIc\^\fB;\fR
.PP
.B isalnum()
tests whether
the argument \fIc\fR is alphanumeric (\fB0\-9\fR, \fBA\-Z\fR, or \fBa\-z\fR).
It returns a number other than zero if \fIc\fR is of the desired type,
and zero if it is not.
.B isalnum()
assumes that \fIc\fR is an ASCII character or EOF.
.SH Example
For an example of how to use this macro, see the entry for
.BR ctype.h .
.SH "See Also"
.Xr "ASCII," ascii
.Xr "libc" libc
.br
\*(AS, \(sc7.3.1.1
.br
\*(PX Standard, \(sc8.1
