C ++函数默认参数的位置

Question

// Case A
class Point {
private:
    int x;
    int y;
public:
    Point(int i = 0, int j = 0);  // Constructor
};

Point::Point(int i, int j)  {
    x = i;
    y = j;
    cout << "Constructor called";
}

// Case B:
class Point {
private:
    int x;
    int y;
public:
    Point(int i, int j);  // Constructor
};

Point::Point(int i = 0, int j = 0)  {
    x = i;
    y = j;
    cout << "Constructor called";
}

Question> Both Case A and Case B compile without problems with VS2010.

Original I assume only Case A works because I remember that the default parameters should be introduced in the place where the function is declared rather than the location of its definition. Can someone correct me on this?

Thank you

Answer 1

If you put the default parameters into the method definition, then only those who see the definition would be able to use the default parameters. The only problem would be if you tried something like this:

public:
    Point(int i = 0, int j = 0);

(...)

Point::Point(int i = 0, int j = 0) { ... }

Then you would get a build-time error.

// EDIT: But I'm curious what Mark B. will find as mentioned in a comment under your question.

// EDIT2: And also apparently clang compiler doesn't like Case B.