io.h源码 检查文件是否存在

 请问在windows上使用什么API来检查文件是否存在？ http://topic.csdn.net/u/20080929/00/48833cf7-125f-4075-881f-614a51fc3e6d.html

搜索这个问题的时候，看到的。

linux下直接open (filename,O_RDONLY) 返回值判断，windows下 没有这个函数？奇怪。貌似有 _open()函数，可以去msdn查去。

查找到windows用 下面的函数就可以。filename是 char * 类型。

if( PathFileExists(filename) ){
return true;
}
return false;

但又看到上面的 床上等你csdn 的讨论，有个io.h _access函数，定义如下。

_Check_return_ _CRTIMP int __cdecl _access(_In_z_ const char * _Filename, _In_ int _AccessMode);

_Check_return_ _CRT_NONSTDC_DEPRECATE(_access) _CRTIMP int __cdecl access(_In_z_ const char * _Filename, _In_ int _AccessMode);

_AccessMode 取值代表的意思，不知道到那里查看。如果有源码也行啊，就是没有。

既然有个 stdio.h 为什么还单独 拿出 io.h呢？ 就不能整合到一起么？

而且我做了个测试，居然有莫名其妙的错误，原来是 c:\ 要写成 c:\\

#include <io.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

bool isFileExist(const char *filename){
    if( _access(filename, 0) == 0 ) {
        // exist
        printf("Exist %s\n",filename);
    }else{
        printf("Not exist %s\n",filename);
    }
    return true;
}

int main(){
    isFileExist("c:\\boot.ini");
    isFileExist("c:\\bootmgr");
    return 0;
}

测试结果：

>gcc test.cpp

>a
Not exist c:\boot.ini
Exist c:\bootmgr

之前的错误 显示结果为：

Not exist coot.ini
Not exist cootmgr

程序大小 49.3KB ，不怎么小。

附上C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\io.h 代码 不明白，条件编译 为什么就不给代码格式化 缩进呢？？？

/***
*io.h - declarations for low-level file handling and I/O functions
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This file contains the function declarations for the low-level
*       file handling and I/O functions.
*
*       [Public]
*
****/

#pragma once

#ifndef _INC_IO
#define _INC_IO

#include <crtdefs.h>

/*
 * Currently, all MS C compilers for Win32 platforms default to 8 byte
 * alignment.
 */
#pragma pack(push,_CRT_PACKING)

#ifndef _POSIX_

#ifdef  __cplusplus
extern "C" {
#endif

#ifndef _FSIZE_T_DEFINED
typedef unsigned long _fsize_t; /* Could be 64 bits for Win32 */
#define _FSIZE_T_DEFINED
#endif

#ifndef _FINDDATA_T_DEFINED

struct _finddata32_t {
        unsigned    attrib;
        __time32_t  time_create;    /* -1 for FAT file systems */
        __time32_t  time_access;    /* -1 for FAT file systems */
        __time32_t  time_write;
        _fsize_t    size;
        char        name[260];
};

struct _finddata32i64_t {
        unsigned    attrib;
        __time32_t  time_create;    /* -1 for FAT file systems */
        __time32_t  time_access;    /* -1 for FAT file systems */
        __time32_t  time_write;
        __int64     size;
        char        name[260];
};

struct _finddata64i32_t {
        unsigned    attrib;
        __time64_t  time_create;    /* -1 for FAT file systems */
        __time64_t  time_access;    /* -1 for FAT file systems */
        __time64_t  time_write;
        _fsize_t    size;
        char        name[260];
};

struct __finddata64_t {
        unsigned    attrib;
        __time64_t  time_create;    /* -1 for FAT file systems */
        __time64_t  time_access;    /* -1 for FAT file systems */
        __time64_t  time_write;
        __int64     size;
        char        name[260];
};

#ifdef _USE_32BIT_TIME_T
#define _finddata_t     _finddata32_t
#define _finddatai64_t  _finddata32i64_t

#define _findfirst      _findfirst32
#define _findnext       _findnext32
#define _findfirsti64   _findfirst32i64
#define _findnexti64     _findnext32i64

#else
#define _finddata_t     _finddata64i32_t
#define _finddatai64_t  __finddata64_t

#define _findfirst      _findfirst64i32
#define _findnext       _findnext64i32
#define _findfirsti64   _findfirst64
#define _findnexti64    _findnext64

#endif


#define _FINDDATA_T_DEFINED
#endif

#ifndef _WFINDDATA_T_DEFINED

struct _wfinddata32_t {
        unsigned    attrib;
        __time32_t  time_create;    /* -1 for FAT file systems */
        __time32_t  time_access;    /* -1 for FAT file systems */
        __time32_t  time_write;
        _fsize_t    size;
        wchar_t     name[260];
};

struct _wfinddata32i64_t {
        unsigned    attrib;
        __time32_t  time_create;    /* -1 for FAT file systems */
        __time32_t  time_access;    /* -1 for FAT file systems */
        __time32_t  time_write;
        __int64     size;
        wchar_t     name[260];
};

struct _wfinddata64i32_t {
        unsigned    attrib;
        __time64_t  time_create;    /* -1 for FAT file systems */
        __time64_t  time_access;    /* -1 for FAT file systems */
        __time64_t  time_write;
        _fsize_t    size;
        wchar_t     name[260];
};

struct _wfinddata64_t {
        unsigned    attrib;
        __time64_t  time_create;    /* -1 for FAT file systems */
        __time64_t  time_access;    /* -1 for FAT file systems */
        __time64_t  time_write;
        __int64     size;
        wchar_t     name[260];
};

#ifdef _USE_32BIT_TIME_T
#define _wfinddata_t    _wfinddata32_t
#define _wfinddatai64_t _wfinddata32i64_t

#define _wfindfirst     _wfindfirst32
#define _wfindnext      _wfindnext32
#define _wfindfirsti64  _wfindfirst32i64
#define _wfindnexti64   _wfindnext32i64

#else                  
#define _wfinddata_t    _wfinddata64i32_t
#define _wfinddatai64_t _wfinddata64_t

#define _wfindfirst     _wfindfirst64i32
#define _wfindnext      _wfindnext64i32
#define _wfindfirsti64  _wfindfirst64
#define _wfindnexti64   _wfindnext64

#endif

#define _WFINDDATA_T_DEFINED
#endif

/* File attribute constants for _findfirst() */

#define _A_NORMAL       0x00    /* Normal file - No read/write restrictions */
#define _A_RDONLY       0x01    /* Read only file */
#define _A_HIDDEN       0x02    /* Hidden file */
#define _A_SYSTEM       0x04    /* System file */
#define _A_SUBDIR       0x10    /* Subdirectory */
#define _A_ARCH         0x20    /* Archive file */

/* function prototypes */

#ifndef _SIZE_T_DEFINED
#ifdef  _WIN64
typedef unsigned __int64    size_t;
#else
typedef _W64 unsigned int   size_t;
#endif
#define _SIZE_T_DEFINED
#endif

_Check_return_ _CRTIMP int __cdecl _access(_In_z_ const char * _Filename, _In_ int _AccessMode);
_Check_return_wat_ _CRTIMP errno_t __cdecl _access_s(_In_z_ const char * _Filename, _In_ int _AccessMode);
_Check_return_ _CRTIMP int __cdecl _chmod(_In_z_ const char * _Filename, _In_ int _Mode);
/* note that the newly added _chsize_s takes a 64 bit value */
_Check_return_ _CRTIMP int __cdecl _chsize(_In_ int _FileHandle, _In_ long _Size);
_Check_return_wat_ _CRTIMP errno_t __cdecl _chsize_s(_In_ int _FileHandle,_In_ __int64 _Size);
_Check_return_opt_ _CRTIMP int __cdecl _close(_In_ int _FileHandle);
_Check_return_opt_ _CRTIMP int __cdecl _commit(_In_ int _FileHandle);
_Check_return_ _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl _creat(_In_z_ const char * _Filename, _In_ int _PermissionMode);
_Check_return_ _CRTIMP int __cdecl _dup(_In_ int _FileHandle);
_Check_return_ _CRTIMP int __cdecl _dup2(_In_ int _FileHandleSrc, _In_ int _FileHandleDst);
_Check_return_ _CRTIMP int __cdecl _eof(_In_ int _FileHandle);
_Check_return_ _CRTIMP long __cdecl _filelength(_In_ int _FileHandle);
_Check_return_ _CRTIMP intptr_t __cdecl _findfirst32(_In_z_ const char * _Filename, _Out_ struct _finddata32_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _findnext32(_In_ intptr_t _FindHandle, _Out_ struct _finddata32_t * _FindData);
_Check_return_opt_ _CRTIMP int __cdecl _findclose(_In_ intptr_t _FindHandle);
_Check_return_ _CRTIMP int __cdecl _isatty(_In_ int _FileHandle);
_CRTIMP int __cdecl _locking(_In_ int _FileHandle, _In_ int _LockMode, _In_ long _NumOfBytes);
_Check_return_opt_ _CRTIMP long __cdecl _lseek(_In_ int _FileHandle, _In_ long _Offset, _In_ int _Origin);
_Check_return_wat_ _CRTIMP errno_t __cdecl _mktemp_s(_Inout_z_cap_(_Size) char * _TemplateName, _In_ size_t _Size);
__DEFINE_CPP_OVERLOAD_SECURE_FUNC_0_0(errno_t, _mktemp_s, _Deref_prepost_z_ char, _TemplateName)
_Check_return_ __DEFINE_CPP_OVERLOAD_STANDARD_FUNC_0_0(char *, __RETURN_POLICY_DST, _CRTIMP, _mktemp, _Inout_z_, char, _TemplateName)
_Check_return_ _CRTIMP int __cdecl _pipe(_Inout_cap_c_(2) int * _PtHandles, _In_ unsigned int _PipeSize, _In_ int _TextMode);
_Check_return_ _CRTIMP int __cdecl _read(_In_ int _FileHandle, _Out_bytecap_(_MaxCharCount) void * _DstBuf, _In_ unsigned int _MaxCharCount);

#ifndef _CRT_DIRECTORY_DEFINED
#define _CRT_DIRECTORY_DEFINED
_CRTIMP int __cdecl remove(_In_z_ const char * _Filename);
_Check_return_ _CRTIMP int __cdecl rename(_In_z_ const char * _OldFilename, _In_z_ const char * _NewFilename);
_CRTIMP int __cdecl _unlink(_In_z_ const char * _Filename);
#if !__STDC__
_CRT_NONSTDC_DEPRECATE(_unlink) _CRTIMP int __cdecl unlink(_In_z_ const char * _Filename);
#endif
#endif

_Check_return_ _CRTIMP int __cdecl _setmode(_In_ int _FileHandle, _In_ int _Mode);
_Check_return_ _CRTIMP long __cdecl _tell(_In_ int _FileHandle);
_CRT_INSECURE_DEPRECATE(_umask_s) _CRTIMP int __cdecl _umask(_In_ int _Mode);
_Check_return_wat_ _CRTIMP errno_t __cdecl _umask_s(_In_ int _NewMode, _Out_ int * _OldMode);
_CRTIMP int __cdecl _write(_In_ int _FileHandle, _In_bytecount_(_MaxCharCount) const void * _Buf, _In_ unsigned int _MaxCharCount);

_Check_return_ _CRTIMP __int64 __cdecl _filelengthi64(_In_ int _FileHandle);
_Check_return_ _CRTIMP intptr_t __cdecl _findfirst32i64(_In_z_ const char * _Filename, _Out_ struct _finddata32i64_t * _FindData);
_Check_return_ _CRTIMP intptr_t __cdecl _findfirst64i32(_In_z_ const char * _Filename, _Out_ struct _finddata64i32_t * _FindData);
_Check_return_ _CRTIMP intptr_t __cdecl _findfirst64(_In_z_ const char * _Filename, _Out_ struct __finddata64_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _findnext32i64(_In_ intptr_t _FindHandle, _Out_ struct _finddata32i64_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _findnext64i32(_In_ intptr_t _FindHandle, _Out_ struct _finddata64i32_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _findnext64(_In_ intptr_t _FindHandle, _Out_ struct __finddata64_t * _FindData);
_Check_return_opt_ _CRTIMP __int64 __cdecl _lseeki64(_In_ int _FileHandle, _In_ __int64 _Offset, _In_ int _Origin);
_Check_return_ _CRTIMP __int64 __cdecl _telli64(_In_ int _FileHandle);

_Check_return_wat_ _CRTIMP errno_t __cdecl _sopen_s(_Out_ int * _FileHandle, _In_z_ const char * _Filename,_In_ int _OpenFlag, _In_ int _ShareFlag, _In_ int _PermissionMode);

#if !defined(__cplusplus)
_Check_return_ _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl _open(_In_z_ const char * _Filename, _In_ int _OpenFlag, ...);
_Check_return_ _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl _sopen(_In_z_ const char * _Filename, _In_ int _OpenFlag, int _ShareFlag, ...);
#else

/* these function do not validate pmode; use _sopen_s */
extern "C++" _Check_return_ _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl _open(_In_z_ const char * _Filename, _In_ int _Openflag, _In_ int _PermissionMode = 0);
extern "C++" _Check_return_ _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl _sopen(_In_z_ const char * _Filename, _In_ int _Openflag, _In_ int _ShareFlag, _In_ int _PermissionMode = 0);

#endif

#ifndef _WIO_DEFINED

/* wide function prototypes, also declared in wchar.h  */

_Check_return_ _CRTIMP int __cdecl _waccess(_In_z_ const wchar_t * _Filename, _In_ int _AccessMode);
_Check_return_wat_ _CRTIMP errno_t __cdecl _waccess_s(_In_z_ const wchar_t * _Filename, _In_ int _AccessMode);
_Check_return_ _CRTIMP int __cdecl _wchmod(_In_z_ const wchar_t * _Filename, _In_ int _Mode);
_Check_return_ _CRT_INSECURE_DEPRECATE(_wsopen_s) _CRTIMP int __cdecl _wcreat(_In_z_ const wchar_t * _Filename, _In_ int _PermissionMode);
_Check_return_ _CRTIMP intptr_t __cdecl _wfindfirst32(_In_z_ const wchar_t * _Filename, _Out_ struct _wfinddata32_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _wfindnext32(_In_ intptr_t _FindHandle, _Out_ struct _wfinddata32_t * _FindData);
_CRTIMP int __cdecl _wunlink(_In_z_ const wchar_t * _Filename);
_Check_return_ _CRTIMP int __cdecl _wrename(_In_z_ const wchar_t * _OldFilename, _In_z_ const wchar_t * _NewFilename);
_CRTIMP errno_t __cdecl _wmktemp_s(_Inout_z_cap_(_SizeInWords) wchar_t * _TemplateName, _In_ size_t _SizeInWords);
__DEFINE_CPP_OVERLOAD_SECURE_FUNC_0_0(errno_t, _wmktemp_s, _Deref_prepost_z_ wchar_t, _TemplateName)
__DEFINE_CPP_OVERLOAD_STANDARD_FUNC_0_0(wchar_t *, __RETURN_POLICY_DST, _CRTIMP, _wmktemp, _Inout_z_, wchar_t, _TemplateName)

_Check_return_ _CRTIMP intptr_t __cdecl _wfindfirst32i64(_In_z_ const wchar_t * _Filename, _Out_ struct _wfinddata32i64_t * _FindData);
_Check_return_ _CRTIMP intptr_t __cdecl _wfindfirst64i32(_In_z_ const wchar_t * _Filename, _Out_ struct _wfinddata64i32_t * _FindData);
_Check_return_ _CRTIMP intptr_t __cdecl _wfindfirst64(_In_z_ const wchar_t * _Filename, _Out_ struct _wfinddata64_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _wfindnext32i64(_In_ intptr_t _FindHandle, _Out_ struct _wfinddata32i64_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _wfindnext64i32(_In_ intptr_t _FindHandle, _Out_ struct _wfinddata64i32_t * _FindData);
_Check_return_ _CRTIMP int __cdecl _wfindnext64(_In_ intptr_t _FindHandle, _Out_ struct _wfinddata64_t * _FindData);

_Check_return_wat_ _CRTIMP errno_t __cdecl _wsopen_s(_Out_ int * _FileHandle, _In_z_ const wchar_t * _Filename, _In_ int _OpenFlag, _In_ int _ShareFlag, _In_ int _PermissionFlag);

#if !defined(__cplusplus) || !defined(_M_IX86)

_Check_return_ _CRT_INSECURE_DEPRECATE(_wsopen_s) _CRTIMP int __cdecl _wopen(_In_z_ const wchar_t * _Filename, _In_ int _OpenFlag, ...);
_Check_return_ _CRT_INSECURE_DEPRECATE(_wsopen_s) _CRTIMP int __cdecl _wsopen(_In_z_ const wchar_t * _Filename, _In_ int _OpenFlag, int _ShareFlag, ...);

#else

/* these function do not validate pmode; use _sopen_s */
extern "C++" _CRT_INSECURE_DEPRECATE(_wsopen_s) _CRTIMP int __cdecl _wopen(_In_z_ const wchar_t * _Filename, _In_ int _OpenFlag, _In_ int _PermissionMode = 0);
extern "C++" _CRT_INSECURE_DEPRECATE(_wsopen_s) _CRTIMP int __cdecl _wsopen(_In_z_ const wchar_t * _Filename, _In_ int _OpenFlag, _In_ int _ShareFlag, int _PermissionMode = 0);

#endif

#define _WIO_DEFINED
#endif

int  __cdecl __lock_fhandle(_In_ int _Filehandle);
void __cdecl _unlock_fhandle(_In_ int _Filehandle);


_CRTIMP intptr_t __cdecl _get_osfhandle(_In_ int _FileHandle);
_CRTIMP int __cdecl _open_osfhandle(_In_ intptr_t _OSFileHandle, _In_ int _Flags);

#if     !__STDC__

/* Non-ANSI names for compatibility */

#pragma warning(push)
#pragma warning(disable: 4141) /* Using deprecated twice */ 
_Check_return_ _CRT_NONSTDC_DEPRECATE(_access) _CRTIMP int __cdecl access(_In_z_ const char * _Filename, _In_ int _AccessMode);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_chmod) _CRTIMP int __cdecl chmod(_In_z_ const char * _Filename, int _AccessMode);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_chsize) _CRTIMP int __cdecl chsize(_In_ int _FileHandle, _In_ long _Size);
_Check_return_opt_ _CRT_NONSTDC_DEPRECATE(_close) _CRTIMP int __cdecl close(_In_ int _FileHandle);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_creat) _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl creat(_In_z_ const char * _Filename, _In_ int _PermissionMode);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_dup) _CRTIMP int __cdecl dup(_In_ int _FileHandle);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_dup2) _CRTIMP int __cdecl dup2(_In_ int _FileHandleSrc, _In_ int _FileHandleDst);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_eof) _CRTIMP int __cdecl eof(_In_ int _FileHandle);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_filelength) _CRTIMP long __cdecl filelength(_In_ int _FileHandle);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_isatty) _CRTIMP int __cdecl isatty(_In_ int _FileHandle);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_locking) _CRTIMP int __cdecl locking(_In_ int _FileHandle, _In_ int _LockMode, _In_ long _NumOfBytes);
_Check_return_opt_ _CRT_NONSTDC_DEPRECATE(_lseek) _CRTIMP long __cdecl lseek(_In_ int _FileHandle, _In_ long _Offset, _In_ int _Origin);
_CRT_NONSTDC_DEPRECATE(_mktemp) _CRT_INSECURE_DEPRECATE(_mktemp_s) _CRTIMP char * __cdecl mktemp(_Inout_z_ char * _TemplateName);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_open) _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl open(_In_z_ const char * _Filename, _In_ int _OpenFlag, ...);
_CRT_NONSTDC_DEPRECATE(_read) _CRTIMP int __cdecl read(int _FileHandle, _Out_bytecap_(_MaxCharCount) void * _DstBuf, _In_ unsigned int _MaxCharCount);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_setmode) _CRTIMP int __cdecl setmode(_In_ int _FileHandle, _In_ int _Mode);
_CRT_NONSTDC_DEPRECATE(_sopen) _CRT_INSECURE_DEPRECATE(_sopen_s) _CRTIMP int __cdecl sopen(const char * _Filename, _In_ int _OpenFlag, _In_ int _ShareFlag, ...);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_tell) _CRTIMP long __cdecl tell(_In_ int _FileHandle);
_CRT_NONSTDC_DEPRECATE(_umask) _CRT_INSECURE_DEPRECATE(_umask_s) _CRTIMP int __cdecl umask(_In_ int _Mode);
_Check_return_ _CRT_NONSTDC_DEPRECATE(_write) _CRTIMP int __cdecl write(_In_ int _Filehandle, _In_bytecount_(_MaxCharCount) const void * _Buf, _In_ unsigned int _MaxCharCount);
#pragma warning(pop)

#endif  /* __STDC__ */

#ifdef  __cplusplus
}
#endif

#endif  /* _POSIX_ */

#pragma pack(pop)

#endif  /* _INC_IO */

这个头文件 外围的条件编译是非 posix。windows平台 还有 CreateFile啊，GetFileAttributeEx啊，FindFirstFile

BOOL FindFirstFileExists(LPCTSTR lpPath, DWORD dwFilter)
{
  WIN32_FIND_DATA fd;
  HANDLE hFind = FindFirstFile(lpPath, &fd);
  BOOL bFilter = (FALSE == dwFilter) ? TRUE : fd.dwFileAttributes & dwFilter;
  BOOL RetValue = ((hFind != INVALID_HANDLE_VALUE) && bFilter) ? TRUE : FALSE;
  FindClose(hFind);
  return RetValue;
}

// 检查一个路径是否存在（绝对路径、相对路径，文件或文件夹均可）
BOOL FilePathExists(LPCTSTR lpPath)
{
  return FindFirstFileExists(lpPath, FALSE);
}

// 检查一个文件夹是否存在（绝对路径、相对路径均可）
BOOL FolderExists(LPCTSTR lpPath)
{
  return FindFirstFileExists(lpPath, FILE_ATTRIBUTE_DIRECTORY);
}

HANDLE FindFirstFileEx(
  LPCTSTR lpFileName, // file name
  FINDEX_INFO_LEVELS fInfoLevelId, // information level
  LPVOID lpFindFileData, // information buffer
  FINDEX_SEARCH_OPS fSearchOp, // filtering type
  LPVOID lpSearchFilter, // search criteria
  DWORD dwAdditionalFlags // reserved
);

 

 

 

都是些 windows平台的函数。不是跨平台的。微软 真是 烦人。