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.Dd July 16, 2004
.Dt FGETWLN 3
.Os
.Sh NAME
.Nm fgetwln
.Nd get a line of wide characters from a stream
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.In wchar.h
.Ft wchar_t *
.Fn fgetwln "FILE * restrict stream" "size_t * restrict len"
.Sh DESCRIPTION
The
.Fn fgetwln
function
returns a pointer to the next line from the stream referenced by
.Fa stream .
This line is
.Em not
a standard wide character string as it does not end with a terminating
null wide character.
The length of the line, including the final newline,
is stored in the memory location to which
.Fa len
points.
(Note, however, that if the line is the last
in a file that does not end in a newline,
the returned text will not contain a newline.)
.Sh RETURN VALUES
Upon successful completion a pointer is returned;
this pointer becomes invalid after the next
.Tn I/O
operation on
.Fa stream
(whether successful or not)
or as soon as the stream is closed.
Otherwise,
.Dv NULL
is returned.
The
.Fn fgetwln
function
does not distinguish between end-of-file and error; the routines
.Xr feof 3
and
.Xr ferror 3
must be used
to determine which occurred.
If an error occurs, the global variable
.Va errno
is set to indicate the error.
The end-of-file condition is remembered, even on a terminal, and all
subsequent attempts to read will return
.Dv NULL
until the condition is
cleared with
.Xr clearerr 3 .
.Pp
The text to which the returned pointer points may be modified,
provided that no changes are made beyond the returned size.
These changes are lost as soon as the pointer becomes invalid.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EBADF
The argument
.Fa stream
is not a stream open for reading.
.El
.Pp
The
.Fn fgetwln
function
may also fail and set
.Va errno
for any of the errors specified for the routines
.Xr mbrtowc 3 ,
.Xr realloc 3 ,
or
.Xr read 2 .
.Sh SEE ALSO
.Xr ferror 3 ,
.Xr fgetln 3 ,
.Xr fgetws 3 ,
.Xr fopen 3