C ++ - front and rear operator operator

I. Pre-operator and the operator post

Q: The following code there is no difference? why?

Code implementation

#include <iostream>
#include <string>

using namespace std;

int main()
{
    int i = 0;

    i++;

    ++i;

    return 0;
}

Unexpected fact
1. modern compilers optimize the code will
2. optimized such that the final binary more efficient
3. optimized missing binary C / C ++ native semantic
4. impossible to restore from the binary program compiled C / C ++ program

Q: ++ operator can override it? How to distinguish between the front and rear + + + +?
++ operator can be overloaded
globally member function can be any function overloading
2. Pre ++ overload operators do not require additional parameters
3. Overload operator needs post ++ type int parameter placeholder
code sample

#include <iostream>
#include <string>

using namespace std;

class Test
{
    int mValue;
public:
    Test(int i)
    {
        mValue = i;
    }

    int value()
    {
        return mValue;
    }

    Test& operator ++ ()//前置操作符
    {
        ++mValue;

        return *this;
    }

    Test operator ++ (int)//后置操作符
    {
        Test ret(mValue);//当前对象的值保存在一个对象中

        mValue++;

        return ret;
    }
};

int main()
{
    Test t(0);
    cout<<t.value()<<endl;
    ++t;
    cout<<t.value()<<endl;

    return 0;
}

Pre-operator operation and operators results shown in Figure rear

of the sample code can be seen that the front and rear operator is the operator there is a difference of
1 for a base type is. - Pre ++ ++ efficiency and the efficiency of the post is substantially the same, rotates according to the coding standard item group
2. for the type of object classes - pre post ++ ++ higher efficiency, mainly because there is no pre-operator call constructor, so try to use the front ++ when using the program to improve efficiency