dos命令
md

系统API
CreateDirectory

int _mkdir( const char *dirname );

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:

EEXIST

Directory was not created because dirname is the name of an existing file, directory, or device

ENOENT

Path was not found

Parameter

dirname

Path for new directory

Remarks

The _mkdir function creates a new directory with the specified dirname. _mkdir can create only one new directory per call, so only the last component of dirname can name a new directory. _mkdir does not translate path delimiters. In Windows NT, both the backslash ( \) and the forward slash (/ ) are valid path delimiters in character strings in run-time routines.

_wmkdir is a wide-character version of _mkdir; the dirname argument to _wmkdir is a wide-character string. _wmkdir and _mkdir behave identically otherwise.

Example

/* MAKEDIR.C */

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

void 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" );
}

Output

Directory '\testtmp' was successfully created   
Volume in drive C is CDRIVE
Volume Serial Number is 0E17-1702

Directory of C:\testtmp

05/03/94  12:30p        <DIR>           .
05/03/94  12:30p        <DIR>           ..
               2 File(s)          0 bytes
                             17,358,848 bytes free
Directory '\testtmp' was successfully removed

感谢楼上两位，
我还想问一下，能不能让c程序运行生成的文件直接放到一个指定的目录(想放在什么目录下就能放在什么目录下,通过程序本身能实现吗???????