Aug 12

C++ 重载operator的示例 By Felix021 不指定

felix021 @ 2008-8-12 03:26 [IT » 程序设计] 评论(0) , 引用(0) , 阅读(5471) | Via 本站原创 | |
C++重载operator的示例 By Felix021

以下示例中定义了一个class test, 重载了<, +, +=, =, ==, <<, >>等符号:

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

class test{
public:
    int v;
  /*构造函数*/
    test():v(0){}
    test(const int &a):v(a){}
    test(const test &t1):v(t1.v){}
    
  /*以下重载小于号 < */
    //比较两个对象的大小
    bool operator<(const test &t1) const{
        return (v < t1.v);
    }
    //比较对象和int的大小
    bool operator<(const int &t1) const{
        return (v < t1);
    }
    //友元函数,比较int和对象的大小
    friend inline bool operator<(const int &a, const test & t1){
        return (a < t1.v);
    }
    
  /*以下重载赋值号 = */
    //对象间赋值
    test & operator=(const test &t1){
        v = t1.v;
        return *this;
    }
    //int赋值给对象
    test & operator=(const int &t1){
        v = t1;
        return *this;
    }
    
  /*以下重载加号 + */
    //对象加上 int
    test operator+(const int & a){
        test t1;
        t1.v = v + a;
        return t1;
    }
    //对象加对象
    test operator+(test &t1){
        test t2;
        t2.v = v + t1.v;
        return t2;
    }
    
  /*以下重载加等号 += */  
    //对象加上对象
    test &operator+=(const test &t1){
        v += t1.v;
        return *this;
    }  
    //对象加上int
    test &operator+=(const int &a){
        v += a;
        return *this;
    }

  /*以下重载双等号 == */  
    //对象==对象
    bool operator==(const test &t1)const{
        return (v == t1.v);
    }  
    //对象==int
    bool operator==(const int &t1)const{
        return (v == t1);
    }  
    
  /*以下重载 输入>> 输出<< */
    /*友元函数,输出对象*/
    friend inline ostream & operator << (ostream & os, test &t1){
        cout << "class t(" << t1.v << ")" << endl;
        return os;
    }
    /*友元函数,输入对象*/
    friend inline istream & operator >> (istream & is, test &t1){
        cin >> t1.v;
        return is;
    }
};

int main(){
    test t0, t1(3);
    test t2(t1);
    cout << t0 << t1 << t2;
    cin >> t1;
    t2 = t1;
    t2 += t1;
    t1 += 10;
    cout << t2;
    if(t1 < t2) cout << "t1 < t2";
    else if(t1 == t2) cout << "t1 = t2";
    else /* t1 > t2*/ cout << "t1 > t2";
    cout <<endl;
    system("pause");
    return 0;
}




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