实验7

11-7

#include <iostream>
using namespace std;
int main()
{
    ios_base::fmtflags original_flags=cout.flags();
    cout<<812<<'|';
    cout.setf(ios_base::left,ios_base::adjustfield);//设置格式标志位，左对齐 
    cout.width(10);  //设置域的宽度为10 
    cout<<813<<815<<'\n';
    cout.unsetf(ios_base::adjustfield);//清除标志位 ，清除十进制 
    cout.precision(2);//设置域的精度为两位 
    cout.setf(ios_base::uppercase|ios_base::scientific);//设置格式标志位，科学计数法 
    cout<<831.0;
    cout.flags(original_flags);
    
    
    return 0;
}

11-3

#include <iostream>
#include<fstream>
using namespace std;
int main()
{
    ofstream out("test1");
    out<<"已经成功写入文件！"<<endl;
    out.close();
    
    return 0; 
}

11-4

#include <iostream>
#include <fstream>
#include<string>
using namespace std;
int main()
{
    string s;   //////////
    
    ifstream in("test1");
    in>>s;        ///////////
    cout<<s<<endl;    //////
    in.close();
    
    
    return 0; 
}

2

#include <iostream>
#include<fstream>
#include<string>
#include<stdlib.h>
#include<time.h>
using namespace std;
int main()
{
    int a[100];string b[100];string c[100],d[100];
    ifstream in("list.txt");
    for(int i=0;i<84;i++){
    in>>a[i]>>b[i]>>c[i]>>d[i];
}
   srand((int)time(0));
   
   for(int i=0;i<5;i++)
   {
       int t=rand()%84+0;
cout<<a[t]<<" "<<b[t]<<" "<<c[t]<<" "<<d[t]<<endl;
   }
    in.close();
    return 0;
}

3