Correct way to initialize vector member variable
See http://en.cppreference.com/w/cpp/language/default_initialization
Default initialization is performed in three situations:
- when a variable with automatic storage duration is declared with no initializer
- when an object with dynamic storage duration is created by a new-expression without an initializer
- when a base class or a non-static data member is not mentioned in a constructor initializer list and that constructor is called.
The effects of default initialization are:
- If T is a class type, the default constructor is called to provide the initial value for the new object.
- If T is an array type, every element of the array is default-initialized.
- Otherwise, nothing is done.
Since std::vector
is a class type its default constructor is called. So the manual initialization isn't needed.
It depends. If you want a size 0 vector, then you don't have to do anything. If you wanted, say, a size N vector fill of 42s then use the constructor initializer lists:
ClassName() : m_vecInts(N, 42) {}