11-7

#include<iostream>
using namespace std;
int main(){
    ios_base::fmtflags original_flags=cout.flags();//保存目前設置 
    cout<<812<<"|";
    cout.setf(ios_base::left,ios_base::adjustfield);//對齊方式改為左對齊 
    cout.width(10);//輸出域寬度改為10 
    cout<<813<<815<<‘\n‘;
    cout.unsetf(ios_base::adjustfield);
 
//清除對齊方式設置 
    cout.precision(2);
    cout.setf(ios_base::uppercase|ios_base::scientific);//更改浮點輸出的顯示方式 
    cout<<831.0;
    cout.flags(original_flags);//恢復之前保存的設置 
    return 0;
}

運行截圖

11-3

#include<iostream>
#include<fstream>
using namespace std;
int main(){
    ofstream file("test1.txt
 
");
    file<<"已成功寫入文件！"<<endl;
    file.close();
    return 0;
}

文件截圖

11-4

#include<iostream>
#include<fstream>
using namespace std;
int main(){
    ifstream file;
    file.open("test1.txt");
    if(!file){cout<<"fail to open"<<endl;}
    char ch;
    while((ch=file.get
 
())!=EOF){cout.put(ch);}
    file.close();
    if(cin>>ch);
    return 0;
}

運行截圖

2.1 代碼

#include<iostream>
#include<fstream>
#include<ctime>
#include<cstdlib>
#include<string>
using namespace std;
class Dice {
public:
    Dice(int a) {sides = a;}
    int cast() {
        int b;
        b = rand() % sides + 1;
        return b;}
private:
    int sides;};
int main() {
    Dice random(83);
    srand(time(NULL));
    ifstream list;
    list.open("list.txt");
    if(!list) cout<<"fail to open"<<endl;
    string info[83],str;
    int i=0,stu;
    while(getline(list,str)){
        info[i]=str;
        i++;
    }
    list.close();
    ofstream roll;
    roll.open("roll.txt");
    for(i=0;i<5;i++){
        stu=random.cast();
        cout<<info[stu-1]<<endl;
        roll<<info[stu-1]<<endl;
    }
    roll.close();
    return 0;
}

運行截圖

實驗7