cpp文件处理

  1 #include <iostream>
  2 #include <fstream>
  3 using namespace std;
  4 
  5 void file_wr(){
  6     char data[100];
  7     //打开文件
  8     ofstream outfile;
  9     outfile.open("demo.dat");
 10     cout<<"write to the file"<<endl;
 11 
 12     cout<<"put in some world one"<<endl;
 13     cin.getline(data,100);
 14 
 15     //向文件输入用户输入值
 16     outfile<<data<<endl;
 17 
 18     cout<<"put in some world two"<<endl;
 19     cin>>data;
 20     cin.ignore();
 21 
 22     //向文件输入用户输入值
 23     outfile<<data<<endl;
 24     outfile.close();//关闭
 25 
 26     //读模式打开
 27     ifstream infile;
 28     infile.open("demo.dat");
 29 
 30     cout<<"read from the file"<<endl;
 31 
 32     infile>>data;
 33     cout<<data<<endl;
 34 
 35     infile>>data;
 36     cout<<data<<endl;
 37 
 38     infile.close();
 39  //   return 0;
 40 }
 41 
 42 int main(){
 43     file_wr();
 44     return 0;
 45 }
 46 
 47 #if 0
 48 class Adder{
 49     public:
 50         //构造函数
 51         Adder(int i=0){
 52             total=i;
 53         }
 54 
 55         void addNum(int number){
 56             total +=number;//在此处累加
 57         }
 58         int getTotal(){
 59             return total;
 60         }
 61     private:
 62         //对外隐藏的数据
 63         int total;
 64 
 65 };
 66 
 67 
 68 //基类
 69 class Box{
 70     public:
 71         //纯虚函数
 72         virtual int getArea()=0;
 73 
 74         void setBreadth(int b){
 75             breadth=b;
 76         }
 77         void setHeight(int h){
 78             height=h;
 79         }
 80         void setLength(int l){
 81             length=l;
 82         }
 83     protected:
 84         int height;
 85         int length;
 86         int breadth;
 87 };
 88 
 89 //派生类
 90 class Renct:public Box{
 91     public:
 92     //与纯虚函数同名
 93         int getArea(){
 94             return (breadth * height *length);
 95         }
 96 };
 97 
 98 class Tenct:public Box{
 99     public:
100     //与纯虚函数同名
101         int getArea(){
102             return (height * length)/2;
103         }
104 };
105 
106 void open(const char *filename,ios::openmode mode){
107 
108 }
109 
110 int main(void)
111 {
112 #if 0
113     Adder b;
114     b.addNum(10);
115     b.addNum(20);
116     b.addNum(50);
117     b.addNum(120);
118 
119     cout<<"Total:"<<b.getTotal()<<endl;
120 #endif
121 
122     Renct acc;
123     Tenct bcc;
124 
125     acc.setBreadth(5);
126     acc.setHeight(4);
127     acc.setLength(3);
128 
129     bcc.setHeight(2);
130     bcc.setLength(3);
131 
132     cout<<"Tenct:"<<acc.getArea()<<endl;
133     cout<<"Teb:"<<bcc.getArea()<<endl;
134 
135     return 0;
136 }
137 #endif