定义计数器类Counter。要求具有以下成员：计数器值；可进行增值和减值记数；可提供记数值。 #include <iostream>

#include <iostream>

using namespace std;

class Counter

{

public:

Counter(int );

Counter operator ++();

Counter operator --();

void display();

private:

int i;

};

Counter::Counter(int a)

{

i=a;

}

void Counter::display()

{

cout<<i;

}

Counter Counter:: operator ++()

{

return Counter (++i);

}

Counter Counter:: operator --()

{

return Counter(--i);

}

int main()

{

Counter C1(5);

cout<<"C1=";C1.display();

++C1;

cout<<endl<<"C1=";C1.display();

--C1;

cout<<endl<<"C1=";C1.display();

cout<<endl;

return 0;

}