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.Dd December 19, 2022
.Dt ISXDIGIT 3
.Os
.Sh NAME
.Nm isxdigit ,
.Nm ishexnumber ,
.Nm isxdigit_l ,
.Nm ishexnumber_l
.Nd hexadecimal-digit character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isxdigit "int c"
.Ft int
.Fn ishexnumber "int c"
.Ft int
.Fn isxdigit_l "int c" "locale_t loc"
.Ft int
.Fn ishexnumber_l "int c" "locale_t loc"
.Sh DESCRIPTION
The
.Fn isxdigit
and
.Fn isxdigit_l
functions test for any hexadecimal-digit character.
Regardless of locale, this includes the following characters only:
.Bl -column \&``0''______ \&``0''______ \&``0''______ \&``0''______ \&``0''______
.It "\&``0''" Ta "``1''" Ta "``2''" Ta "``3''" Ta "``4''"
.It "\&``5''" Ta "``6''" Ta "``7''" Ta "``8''" Ta "``9''"
.It "\&``A''" Ta "``B''" Ta "``C''" Ta "``D''" Ta "``E''"
.It "\&``F''" Ta "``a''" Ta "``b''" Ta "``c''" Ta "``d''"
.It "\&``e''" Ta "``f''" Ta \& Ta \& Ta \&
.El
.Pp
The
.Fn ishexnumber
and
.Fn ishexnumber_l
functions behave similarly to
.Fn isxdigit
and
.Fn isxdigit_l ,
but may recognize additional characters,
depending on the current locale setting.
.Pp
The value of the argument must be representable as an
.Vt "unsigned char"
or the value of
.Dv EOF .
.Pp
The _l-suffixed versions take an explicit locale argument, whereas the
non-suffixed versions use the current global or per-thread locale.
.Sh RETURN VALUES
The
.Fn isxdigit
and
.Fn isxdigit_l
functions return zero if the character tests false and
return non-zero if the character tests true.
.Sh COMPATIBILITY
The
.Bx 4.4
extension of accepting arguments outside of the range of the
.Vt "unsigned char"
type in locales with large character sets is considered obsolete
and may not be supported in future releases.
The
.Fn iswxdigit
or
.Fn iswxdigit_l
function should be used instead.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr ctype_l 3 ,
.Xr iswxdigit 3 ,
.Xr iswxdigit_l 3 ,
.Xr xlocale 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isxdigit
function conforms to
.St -isoC .
.Sh HISTORY
The
.Fn ishexnumber
function appeared in
.Bx 4.4 .