_access()函数检测文件或文件夹是否存在，_mkdir()创建目录。

MSDN 对于_access()函数的介绍：




int _access( const char *path, int mode );  Required header：<io.h>，Optional headers：<errno.h>

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

/* 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 " );
/* Check for write permission */
if( (_access( "ACCESS.C", 2 )) != -1 )
printf( "File ACCESS.C has write permission " );
}
}

Creates a new directory.

int _mkdir(  const char *dirname );

Required header : <direct.h>

Return Value



Each of these functions returns the value 0 if the new directory was created. On an error, the function returns –1 and sets errno as follows

Example

// crt_makedir.c

#include <direct.h>
#include <stdlib.h>
#include <stdio.h>

int main( void )
{
if( _mkdir( "\\testtmp" ) == 0 )
{
printf( "Directory '\\testtmp' was successfully created\n" );
system( "dir \\testtmp" );
if( _rmdir( "\\testtmp" ) == 0 )
printf( "Directory '\\testtmp' was successfully removed\n"  );
else
printf( "Problem removing directory '\\testtmp'\n" );
}
else
printf( "Problem creating directory '\\testtmp'\n" );
}