What's the differences between member initializer list and default member initializer on non-static data member?

Question

I\'d like to understand what\'s the differences of using one form rather than the other (if any).

Code 1 (init directly on variables):

#include 

        

Answer 1

There is no difference in the code. The difference would come if you would be would have more than one constructor overload and in more than one count would be 10. With the first version you would have less writing to do.

class Test 
{
public:
    Test() = default;
    Test(int b) : b(b) {} // a = 1, c = 3

    ~Test();

private:
    int a = 1;
    int b = 2;
    int c = 3;
};

As opposed to the second version where the above code would look like this:

class Test 
{
public:
    Test() : a(1), b(2), c(3) {}
    Test(int b) : a(1), b(b), c(3) {}

    ~Test();

private:
    int a;
    int b;
    int c;
};

The difference gets bigger with more member variables.