Properties declared next to the constructor

Question

I am very new to C / C ++ and do not know what this method is called. But that’s why I’m trying to find the answer here. let me show you an example

MyClass::MyClass() : valueOne(1), valueTwo(2)
{
      //code
}

Where valueOne and valueTwo are class properties that are assigned values ​​outside the body, which method is called, and why it is done this way. Why not do it like this.

MyClass::MyClass()
{
      valueOne = 1;
      valueTwo = 2
      //code
}

If anyone can help me, it will be great.

Answer 1

This is a list of initializers . You can initialize member variables using the list of initializers after the constructor.

, -, . , . , - , .

Answer 2

( ) . , .

Answer 3

. ( ) ( , int).

Answer 4

It is preferable to initialize items in the initializer list. In your case, it does not matter, but it is impossible to initialize int & as you did in the second code fragment. This is the only place where you can also pass arguments to your base class constructor.

Answer 5

Also note that this pointer is available in the initializer list if it is used to refer to data fields or member functions only in BASE classes.