实验7

#include<iostream>
#include<fstream>
#include<cstdlib> 
using namespace std;
int main()
{
    ofstream myFile("test1.txt");
    myFile<<"已成功写入文件！";
    myFile.close();
    char ch;
    ifstream File("test1.txt");
    while (File.get(ch))
        cout<<ch;
    File.close();
    system("pause");
    return 0;
    }

#include<iostream>
#include<cstdlib>
#include<cmath>
#include<ctime>
#include<fstream>
#define N 5
using namespace std;
int main()
{
srand( (unsigned int)time(NULL));
int num[N];
for(int i=0;i<N;i++)
{
    num[i]=rand()%83;
    for(int j=0;j<i;j++)
    {
        if(num[i]==num[j])
        i--; 
    }
}
cout<<"5 numbers choosed:"<<endl;
for(int i=0;i<N;i++)
cout<<num[i]<<endl;
struct stu
{
    int number;
    string id;
    string name;
    string grade;
};
stu student[200];
    ifstream file("list");
    if (file) {
        cout << "file can‘t open" << endl;
        return 1;
    }
    int i = 1;
    while (file >> student[i++].number >> student[i++].id >> student[i++].name >> student[i++].grade) 
    file.close();
    ofstream file1("result.txt");
    for (int i = 0; i < 5; i++) {
        cout << student[num[i]].number << " " << student[num[i]].id << " " << student[num[i]].name << " " << student[num[i]].grade << endl;
       file1 << student[num[i]].number << " " << student[num[i]].id << " " << student[num[i]].name << " " << student[num[i]].grade << endl;
    }
    file1.close();
    return 0;
}

#include<iostream>
#include<cstdlib>
using namespace std;
int main()
{
    ios_base::fmtflags original_flags=cout.flags();//输出格式为枚举型
    cout<<812<<‘|‘;
    cout.setf(ios_base::left,ios_base::adjustfield );//输出格式左对齐
    cout.width (10);                              //输出宽度为10
    cout<<813<<815<<‘\n‘;
    cout.unsetf (ios_base::adjustfield );      //清除对齐方式
    cout.precision (2);
    cout.setf (ios_base ::uppercase |ios_base ::scientific );//对十六进制输出使用大写字母，E表示法，并用科学计数法表示
    cout<<831.0;
    cout.flags (original_flags );//恢复原来的格式化参数设置
    return 0;