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.Dd December 19, 2022
.Dt ISBLANK 3
.Os
.Sh NAME
.Nm isblank ,
.Nm isblank_l
.Nd space or tab character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isblank "int c"
.Ft int
.Fn isblank_l "int c" "locale_t loc"
.Sh DESCRIPTION
The
.Fn isblank
and
.Fn isblank_l
functions test for a space or tab character.
For any locale, this includes the following standard characters:
.Bl -column XXXX
.It Do \et Dc Ta Dq " "
.El
.Pp
In the "C" locale, a successful
.Fn isblank
or
.Fn isblank_l
test is limited to these characters only.
The value of the argument must be representable as an
.Vt "unsigned char"
or the value of
.Dv EOF .
.Pp
The
.Fn isblank_l
function takes an explicit locale argument, whereas the
.Fn isblank
function uses the current global or per-thread locale.
.Sh RETURN VALUES
The
.Fn isblank
and
.Fn isblank_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 iswblank
or
.Fn iswblank_l
function should be used instead.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr ctype_l 3 ,
.Xr iswblank 3 ,
.Xr iswblank_l 3 ,
.Xr xlocale 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isblank
function
conforms to
.St -isoC-99 .
The
.Fn isblank_l
function conforms to
.St -p1003.1-2008 .