跨平台查询文件时间，如果超过7天，删除该文件（windows和linxu测试过）

windows调用的是_stat函数，linux调用的是stat函数。

#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <errno.h>

int main( void )
{
   int result;
   char* filename = "putty.exe";
   //errno_t err;
#ifdef WIN32
   struct _stat buf;
   result = _stat( filename, &buf );
#else
   struct stat buf;
   result = stat(filename, &buf);
#endif

   if( result !=  )
   {
      perror( "Problem getting information" );
      switch (errno)
      {
         case ENOENT:
           printf("File %s not found.\n", filename);
           break;
         case EINVAL:
           printf("Invalid parameter to _stat.\n");
           break;
         default:
           /* Should never be reached. */
           printf("Unexpected error in _stat.\n");
      }
   }
   else
   {
      // Output some of the statistics:
      printf( "File size     : %ld\n", buf.st_size );
      printf( "Drive         : %c:\n", buf.st_dev + 'A' );

      time_t t;
      tzset(); /*tzset()*/
      t = time(NULL);
      if((t - buf.st_mtime) > )//604800是7天的秒数，下面是删除超过7天的文件
      {
        remove(filename);
        printf("remove file : %s \n" ,filename);
      }

   }

}