Why can't member variable be initialized?

[acppdummy]

Not quite: this is initialisation, but assigning in the body of the constructor is assignment. This is an important difference when the member variable is const or of a reference type, and also if the member variable is of a class type whose default constructor does something significant (or which does not have a default constructor). In Lindley's example, it is merely of a built-in type, so there is pretty much no net difference.

Thank you! There is sill a lot for me to learn. So bottom line if the member variable is just simple int or double type then either way is fine, right?