c++前缀和后缀++

///////////////////////////////////////////////////////////////////////////////
//
//  FileName    :   meffect_item5.h
//  Version     :   0.10
//  Author      :   Ryan Han
//  Date        :   2013/11/18
//  Comment     :  prefix and postfix
//
///////////////////////////////////////////////////////////////////////////////
#ifndef MEFFECT_ITEM5_H
#define    MEFFECT_ITEM5_H
#include <iostream>
using namespace std;

class A{
    friend ostream& operator <<(ostream &os, const A &a);
public:
    A(int initvalue=0, int initstep=1):value(initvalue), step(initstep){}

    //prefix
    A& operator++(){
        cout << "A& operator++() was called" << endl;
        value+=step;
        return *this;
    }

    //postfix
    const A operator++(int){
        cout << "const A operator++(int) was called." << endl;
        const A oldA = *this;
        ++(*this);
        return oldA;
    }
private:
    int value;
    int step;
};

#endif

///////////////////////////////////////////////////////////////////////////////
//
//  FileName    :   meffect_item5.cpp
//  Version     :   0.10
//  Author      :   Ryan Han
//  Date        :   2013/11/18
//  Comment     :  prefix and postfix
//
///////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include "meffect_item5.h"
using namespace std;

ostream& operator<<(ostream &os, const A&a)
{
    return os<<a.value;
}
int main(){
    int i = 5;

    //postfix return a const value
    //i++++;
    
    //prefix return a reference
    ++++i;

    A a(0,10);
    cout << a++ << endl;
    cout << ++a << endl;
    A b(0,10);
    cout << b.operator++(9) << endl;
    cout << b.operator++() << endl;

    return 0;
}