在编写函数时，要进行反复的考查，并且自问： “我打算做哪些假定？”

在编写函数时，要进行反复的考查，并且自问： “我打算做哪些假定？”

一旦确定了的假定，就要使用断言对假定进行检查。

#include <iostream>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
/* run this program using the console pauser or add your own getch, system("pause") or input loop */

using namespace std;
int main(int argc, char** argv) {
    struct stat buf;
    int result;

    //获得c:WindowsCalc.exe文件的状态信息
    result =stat( "c:\windows\Calc.exe", &buf );

    //显示Calc.exe文件的状态信息
   if( result != 0 )
       perror( "Problem getting information" );
    else
    {
        cout<<"Size of the file in bytes:"<<buf.st_size<<endl;
        cout<<"Drive number of the disk containing the file :";
        cout<<char(buf.st_dev + 'A')<<endl;
        cout<<"Time of creation of the file:"<<ctime(&buf.st_ctime);
        cout<<"Time of last access of the file:"<<ctime(&buf.st_atime);
        cout<<"Time of last modification of the file:"<<ctime(&buf.st_mtime);
   }
    return 0;
}