第七次实验

Posted 2020-11-19 tacore

//11-7 
#include<iostream>
using namespace std;
int main()
{
    ios_base::fmtflags original_flags=cout.flags();
//    flag指针？指向开头？ 
    cout<<812<<‘|‘;
    cout.setf(ios_base::left,ios_base::adjustfield);
//  输出左对齐 
    cout.width(10);
//  输出长度位10 
    cout<<813<<815<<‘
‘;
    cout.unsetf(ios_base::adjustfield);
//  调整,取消左对齐 
    cout.precision(2);
    cout.setf(ios_base::uppercase|ios_base::scientific);
//  科学计数法表示,并且小数点后保留两位有效数字 
    cout<<831.0;
    cout.flags(original_flags);    
    return 0;
}

//11-8 
#include<fstream>
#include<iostream>
#include<string>
using namespace std;
int main()
{
    ofstream fout("text1.txt");
    if(!fout){
        cout << "fail to build" << endl;
        return 0;
    }
    fout << "已成功写入文件！";
    fout.close();
    return 0;
}

//11-9 
#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    string s;
    ifstream fin("text1.txt");
    if(!fin){
        cout << "fail to open" << endl;
        return 0;
    }
    fin >> s;
    cout << s <<endl;
    fin.close();
    return 0;
} 

//应用练习1
#include<iostream>
#include<fstream>
#include<vector> 
#include<ctime>
#include<string>
using namespace std;
struct stu
{
    string i1;
    string i2;
    string i3;
    string i4;
};
int main()
{
    ifstream fin("list.txt");
    stu k;
    vector<stu> tar;
    if(!fin){
        cout << "fail to open"<<endl;
        return 0;
    }
    string i1,i2,i3,i4; 
    while(fin >> i1 >> i2 >> i3 >> i4){
        k.i1=i1,k.i2=i2,k.i3=i3,k.i4=i4;
        tar.push_back(k);
    }
    fin.close();
    vector<stu> d; 
    srand((unsigned)time(NULL));
    while(d.size()<5){
        d.push_back(tar[rand()%83]);
    } 
    ofstream fout("roll.txt");
    for(int i=0;i<d.size();i++){
        fout << d[i].i1 << "  " << d[i].i2 << "  ";
        fout << d[i].i3 << "  " << d[i].i4 << endl;
    }
    fout.close();
    return 0;
} 

//应用练习2
#include<iostream>
#include<string>
#include<fstream>
using namespace std;
int main()
{
    ifstream fin1("num1.txt");
    char ch,prech=‘
‘;
    int line=0,word=0,words=0;
    while((ch=fin1.get())!=EOF){
        if(ch==‘
‘)line++;
        if(ch!=‘ ‘&&ch!=‘
‘)word++;
        if((prech==‘ ‘&&ch!=‘ ‘)||(prech==‘
‘&&ch!=‘ ‘))words++;
        prech=ch;
    }
    cout << "num.txt has "<< word << " word" << endl;
    cout << "num.txt has "<< words << " words" << endl;
    cout << "num.txt has "<< line << " line" << endl;
    return 0;
}