cpp文件处理

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

void file_wr(){
    char data[100];
    //打开文件
    ofstream outfile;
    outfile.open("demo.dat");
    cout<<"write to the file"<<endl;

    cout<<"put in some world one"<<endl;
    cin.getline(data,100);

    //向文件输入用户输入值
    outfile<<data<<endl;

    cout<<"put in some world two"<<endl;
    cin>>data;
    cin.ignore();

    //向文件输入用户输入值
    outfile<<data<<endl;
    outfile.close();//关闭

    //读模式打开
    ifstream infile;
    infile.open("demo.dat");

    cout<<"read from the file"<<endl;

    infile>>data;
    cout<<data<<endl;

    infile>>data;
    cout<<data<<endl;

    infile.close();
 //   return 0;
}

int main(){
    file_wr();
    return 0;
}

#if 0
class Adder{
    public:
        //构造函数
        Adder(int i=0){
            total=i;
        }

        void addNum(int number){
            total +=number;//在此处累加
        }
        int getTotal(){
            return total;
        }
    private:
        //对外隐藏的数据
        int total;

};


//基类
class Box{
    public:
        //纯虚函数
        virtual int getArea()=0;

        void setBreadth(int b){
            breadth=b;
        }
        void setHeight(int h){
            height=h;
        }
        void setLength(int l){
            length=l;
        }
    protected:
        int height;
        int length;
        int breadth;
};

//派生类
class Renct:public Box{
    public:
    //与纯虚函数同名
        int getArea(){
            return (breadth * height *length);
        }
};

class Tenct:public Box{
    public:
    //与纯虚函数同名
        int getArea(){
            return (height * length)/2;
        }
};

void open(const char *filename,ios::openmode mode){

}

int main(void)
{
#if 0
    Adder b;
    b.addNum(10);
    b.addNum(20);
    b.addNum(50);
    b.addNum(120);

    cout<<"Total:"<<b.getTotal()<<endl;
#endif

    Renct acc;
    Tenct bcc;

    acc.setBreadth(5);
    acc.setHeight(4);
    acc.setLength(3);

    bcc.setHeight(2);
    bcc.setLength(3);

    cout<<"Tenct:"<<acc.getArea()<<endl;
    cout<<"Teb:"<<bcc.getArea()<<endl;

    return 0;
}
#endif