c++中文件的读写（从一个文件读到另一个文件）

#include<iostream>//.h
#include<fstream>
using namespace std;
class uer
{
    public:
    string name,pwd;

    void save(string s)
    {
        ofstream out;
        out.open("data.txt",ios::app);
        out<<s<<endl;
        cout<<s<<endl;
        out.close();
    }
    void get()
    {
        ifstream get("data.txt",ios::in);
        ofstream write("get.txt",ios::app);
        char st[1000];
        while(!write.eof())
        {
            get.getline(st,sizeof(st),'\n');
            write<<st<<endl;
            cout<<st<<endl;
        }
        write.close();
        get.close();
    }
};




#include<fstream>//.cpp
#include<iostream>
#include"uer.h"
using namespace std;
int main()
{
    int n,m;
    string s="123,deng";
    int p=s.find(',',0);
    string s1=s.substr(0,p);
    string s2=s.substr(p+1,s.size());
    uer u;
    u.save(s1);
    u.save(s2);
    u.get();

    return 0;
}