filelength-filelengthi64.md

description	Learn more about: _filelength, _filelengthi64
title	_filelength, _filelengthi64
ms.date	4/2/2020
api_name	_filelengthi64 _filelength _o__filelength _o__filelengthi64
api_location	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-stdio-l1-1-0.dll
api_type	DLLExport
topic_type	apiref
f1_keywords	_filelength _filelengthi64 filelengthi64
helpviewer_keywords	filelengthi64 function lengths, file filelength function _filelength function files [C++], length _filelengthi64 function
ms.assetid	3ab83d5a-543c-4079-b9d9-0abfc7da0275

_filelength, _filelengthi64

Gets the length of a file.

Syntax

long _filelength(
   int fd
);
__int64 _filelengthi64(
   int fd
);

Parameters

fd
Target the file descriptor.

Return value

Both _filelength and _filelengthi64 return the file length, in bytes, of the target file associated with fd. If fd is an invalid file descriptor, this function invokes the invalid parameter handler, as described in Parameter validation. If execution is allowed to continue, both functions return -1L to indicate an error and set errno to EBADF.

Remarks

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function	Required header
_filelength	<io.h>
_filelengthi64	<io.h>

For more compatibility information, see Compatibility.

Example

See the example for _chsize.

See also

File handling
_chsize
_fileno
_fstat, _fstat32, _fstat64, _fstati64, _fstat32i64, _fstat64i32
_stat, _wstat functions