Why is the copy constructor not called?

Question

class MyClass
{
public:
  ~MyClass() {}
  MyClass():x(0), y(0){} //default constructor
  MyClass(int X, int Y):x(X), y(Y){} //user-defined constructor
  MyClass(cons         


        

Answer 1

Apart from what Potatoswatter and Andrey T. has said, note that you can coax most compilers not to elide constructors. GCC typically provides you with -fno-elide-constructors and MSVC with /Od which should give you the desired output. Here's some code:

#include 

#define LOG() std::cout << __PRETTY_FUNCTION__ << std::endl // change to __FUNCSIG__ on MSVC > 2003

class MyClass
{
public:
  ~MyClass() { LOG(); }
  MyClass():x(0), y(0){LOG(); } //default constructor
  MyClass(int X, int Y):x(X), y(Y){LOG(); } //user-defined constructor
  MyClass(const MyClass& tempObj):x(tempObj.x), y(tempObj.y){LOG(); } //copy constructor

private:
int x; int y;
};

int main()
{
 MyClass MyObj(MyClass(1, 2)); //User-defined constructor was called.
 MyClass MyObj2(MyObj); //Copy constructor was called.
}

Compiled with GCC 4.5.0 on MingW32:

 g++ -Wall -pedantic -ansi -pedantic tmp.cpp -o tmp -fno-elide-constructors

Output:

$ tmp.exe
MyClass::MyClass(int, int)
MyClass::MyClass(const MyClass&)
MyClass::~MyClass()
MyClass::MyClass(const MyClass&)
MyClass::~MyClass()
MyClass::~MyClass()