time(& now); printf( " size of time_t: %d\r\n " , sizeof (time_t)); //1 printf( " %d -> %d\r\n " , now, now); // Error 2. printf( " %I64d -> %I64d\r\n " , now, now); // for windows 3. printf( " %lld -> %lld\r\n " , now, now); // for linux 4. return 0 ;

size of time_t: 8
1350547419 -> 0
1350547419 -> 1350547419
1350547419 -> 1350547419

第二个printf参数把把time_t结构分成了两个32位的INT。所以这二个参数为0。