用_access判断文件或文件夹是否存在及其读写权限

摘自MSDN,以前一直没用过这个函数,今天调试程序发现了这个函数,感觉挺好用,尤其是判断一个文件或文件夹是否存在的时候,用不着再find了,文件的话还可以检测读写权限,文件夹的话则只能判断是否存在

int _access( const char *path, int mode );

Return Value

Each of these functions returns 0 if the file has the given mode. The function returns –1 if the named file does not exist or is not accessible in the given mode; in this case, errno is set as follows:

EACCES

Access denied: file’s permission setting does not allow specified access.

ENOENT

Filename or path not found.

Parameters

path

File or directory path

mode

Permission setting

Remarks

When used with files, the _access function determines whether the specified file exists and can be accessed as specified by the value of mode. When used with directories, _access determines only whether the specified directory exists; in Windows NT, all directories have read and write access.

mode Value            Checks File For
00                              Existence only
02                              Write permission
04                              Read permission
06                              Read and write permission

Example

/* ACCESS.C: This example uses _access to check the * file named "ACCESS.C" to see if it exists and if * writing is allowed. */#include  <io.h>#include  <stdio.h>#include  <stdlib.h>void main( void ){   /* Check for existence */   if( (_access( "ACCESS.C", 0 )) != -1 )   {      printf( "File ACCESS.C exists/n" );      /* Check for write permission */      if( (_access( "ACCESS.C", 2 )) != -1 )         printf( "File ACCESS.C has write permission/n" );   }}

Output

File ACCESS.C existsFile ACCESS.C has write permission