C++: Should I initialize pointer members that are assigned to in the constructor body to NULL?

Question

Suppose I have:

// MyClass.h
class MyClass
{
  public:
    MyClass();

  private:
    Something *something_;
}

// MyClass.cpp
MyClass::MyClass()
{
  something_ = new Something();
}

Should I initialize something_ to NULL (or 0) in the constructor initialization list of the MyClass constructor? Or is that not necessary because I'm assigning to it in the body of the constructor? What is the recommended practice?

Answer 1

Generally you only assign it once, in the initialization list or the body, unless the body initialization may or may not happen, or has prerequisite code:

MyClass::MyClass() 
{
   //this code must happen first
   // _now_ max is known
   something_ = new Something(max);
}

MyClass::MyClass() 
{
   if (max) 
       something_ = new Something(max);
   else
       something_ = NULL;
}

MyClass::MyClass() 
    : something_(new Something()) 
//as pointed out in the comments, use smart pointers
{
}