_access

All versions of the C run-time libraries.
Example
This example uses _access to check the file named crt_ACCESS.C to see if it exists
and if writing is allowed.
// crt_access.c
#include  <io.h>
#include  <stdio.h>
#include  <stdlib.h>

int main( void )
{
   /* Check for existence */
   if( (_access( "crt_ACCESS.C",  0  )) != - 1  )
   {
      printf( "File crt_ACCESS.C exists\n" );
      /* Check for write permission */
      /* assume file is read-only */
      if( (_access( "crt_ACCESS.C",  2  )) == - 1  )
         printf( "File crt_ACCESS.C does not have write permission\n" );
   }
}