C++实验23

一、读写数值数据文件

#include<iostream>
using namespace std;
#include<fstream>

void main()
{
    fstream fin;
    fin.open("studentgrade.txt",ios::in);
    if(!fin)
    {
        cout<<"Open file filed"<<endl;
        return;
    }
    int a;
    int sum[3]={0};
    int i = 0;
    fin>>a;
    while(!fin.eof())//读到文本文件的结束符时结束
    {
        sum[i % 3] += a;
        i++;
        fin>>a; //fin>>a放到循环前面，则sum[i % 3] += a多执行一次
    }
    fin.close();

    fstream fout("studentgrade.txt",ios::app);
    fout<<"total:\n";
    fout<<sum[0]<<" "<<sum[1]<<" "<<sum[2]<<endl;
    fout<<"Average:\n";
    fout<<float(sum[0])/(i/3)<<" "<<float(sum[1])/(i/3)<<" "<<float(sum[2])/(i/3)<<endl;
    fout.close();
}

二、字符数据文本读写

#include<iostream>
using namespace std;
#include<string>
#include<fstream>


void main()
{
    string filename;
    cin>>filename;
    ifstream fin(filename,ios::_Nocreate);
    string s_max;
    string s_min;
    int max = 0;
    int min = 100000;
    int max_linenum = 0;
    int min_linenum = 0;

    string s;

    int i = 1;
    while(!fin.eof())
    {
        getline(fin,s);

        if(s.size() < min)
        {
            s_min = s;
            min = s.size();
            min_linenum = i;
        }
        if(s.size() > max)
        {
            s_max = s;
            max = s.size();
            max_linenum = i;
        }
        cout<<i++<<": ";
        cout<<s<<endl;
    }
    fin.close();

    cout<<"\nTotalLine is "<<i-1<<endl;
    cout<<"MaxLine is "<<max_linenum<<":"<<s_max<<"\n"<<s_max.size()<<" characters;\n";
    cout<<"MinLine is "<<min_linenum<<":"<<s_min<<"\n"<<s_min.size()<<" characters;\n";
}