Thread: Creating an object without default constructor

Hi.

I have a question about the default constructor.

To my best understanding, the compiler will provide me with a deafult constructor only if there are no any user defined constructors, at all.

now consider the following code:

Code:

class MyClass
{
private:
    int m_data;
public:
    MyClass(int init):m_data(init){cout<<"Ctr called"<<endl;}
};

int main()
{
    MyClass obj;
}

this code won't compile, since there is "no matching function for call to 'MyClass::MyClass()'".
so far, everything makes sense, since there is no deafult constructor, I can't instantiate a MyClass object without providing one int parameter.

what confusing me is that this code will compile:

Code:

class MyClass
{
private:
    int m_data;
public:
    MyClass(int init):m_data(init){cout<<"Ctr called"<<endl;}
};

int main()
{
    MyClass obj(); //added parentheses
}

How is it that suddenly, there is a default constructor?

if you define a constructor of any kind, the compiler will not generate the default or copy constructor for you. if you define one, you have to define them all yourself.