How to call C++ static method

c++ static-methods
Lee picture Lee · Jul 30, 2009 · Viewed 29.5k times · Source

Is it possible to return an object from a static method in C++ like there is in Java? I am doing this:

class MyMath {
    public:
       static MyObject calcSomething(void);
    private:
};

And I want to do this:

int main() { 
    MyObject o = MyMath.calcSomething(); // error happens here
}

There are only static methods in the MyMath class, so there's no point in instantiating it. But I get this compile error:

MyMath.cpp:69: error: expected primary-expression before '.' token

What am I doing wrong? Do I have to instantiate MyMath? I would rather not, if it is possible.

Answer

Paul picture Paul · Jul 30, 2009

Use :: instead of .

MyObject o = MyMath::calcSomething();

When you are calling the method without the object of the class you should use :: notation. You may also call static method via class objects or pointers to them, in this case you should use usual . or -> notation:

MyObject obj;
MyObject* p = new MyObject();

MyObject::calcSomething();
obj.calcSomething();
p->calcSomething();

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