一.对下标运算符[]的重载:
重载的格式:返回类型 类名 operator [](参数);
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#include<iostream>
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using namespace std;
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class A
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{
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public:
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A(int n);
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~A();
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int & operator [](int n);//返回类型为int & 引用类型
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private:
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int *p;
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int size;
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};
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int & A::operator[](int n){
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return p[n];//返回p[n]
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}
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A::A(int n)
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{
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p = new int[n];
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}
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A::~A()
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{
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delete[]p;
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}
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int main(){
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A a(5);
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a[3] = 4;//等价于a.operator[](3)=4,相当于4赋值给了p[3];
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cout << "a[3]=" << a[3] << endl;
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cin.get();
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return 0;
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}
二.对()运算符的重载
#include<iostream>
using namespace std;
class A{
public:
float operator()(double a,double b);
};
float A::operator ()(double a,double b){
return a*b;
}
int main(){
A f;
float a=f(10.0,1.23);//默认double类型
cout<<a<<endl;
return 0;
}
三.对流输出运算符‘<<’和流输出‘>>’的重载
#include<iostream>
using namespace std;
class A
{
public:
A(int n);
~A();
int& operator[](int);//这里用返回值类型为引用类型,完全是效率问题。
friend ostream& operator <<(ostream &otput, A& a);//对<<的重载最好用友员函数
friend istream& operator >>(istream &input, A& b);
private:
int *p;
int size;
};
int& A::operator[](int a){
if (a<size&&a>=0)
return p[a];
cout << "out of size" << endl;
exit(0);
}
ostream& operator <<(ostream &otput, A& a){
for (int i = 0; i < a.size; i++)
otput << a.p[i]<<' ';
cout << endl;
return otput;
}
istream& operator >>(istream &input, A& b){
for (int i = 0; i < b.size; i++){
input >> b.p[i];
}
return input;//这里返回值为istream 类型变量是规定。
}
A::A(int n)
{
p = new int[n];
size = n;
}
A::~A()
{
delete[]p;
size = 0;
}
int main(){
A a(5);
cout << "input the elements of A a" << endl;
cin >> a;
//cout << "a[5]" << a[5]<<endl;//直接退出。
cout << "a[3]=" << a[3] << endl;
cout << a<<endl;
system("pause");
return 0;
}
本文转自 神迹难觅 51CTO博客,原文链接:http://blog.51cto.com/ji123/1915670,如需转载请自行联系原作者