---
name: "fwide"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/fwide"
---

# fwide(3)

get/set orientation of a stream

## NAME

**fwide** – get/set orientation of a stream

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<stdio.h\>**

**#include \<wchar.h\>**

*int*\

**fwide**(*FILE \*stream*, *int mode*);

## DESCRIPTION

The **fwide**() function determines the orientation of the stream pointed at by *stream*.

If the orientation of *stream* has already been determined, **fwide**() leaves it unchanged. Otherwise, **fwide**() sets the orientation of *stream* according to *mode*.

If *mode* is less than zero, *stream* is set to byte-oriented. If it is greater than zero, *stream* is set to wide-oriented. Otherwise, *mode* is zero, and *stream* is unchanged.

## RETURN VALUES

The **fwide**() function returns a value according to orientation after the call of **fwide**(); a value less than zero if byte-oriented, a value greater than zero if wide-oriented, and zero if the stream has no orientation.

## SEE ALSO

[ferror(3)](/ferror/3.md), [fgetc(3)](/fgetc/3.md), [fgetwc(3)](/fgetwc/3.md), [fopen(3)](/fopen/3.md), [fputc(3)](/fputc/3.md), [fputwc(3)](/fputwc/3.md), [freopen(3)](/freopen/3.md), [stdio(3)](/stdio/3.md)

## STANDARDS

The **fwide**() function conforms to ISO/IEC 9899:1999 (“ISO C99”).