Question

This may be a silly question, but still I’m a bit curious…
Recently I was working on one of my former colleague projects, and I’ve noticed that he really loved to use something like this:

int foo(7);

instead of:

int foo = 7;

Is this a normal/good way to do in C++ language?
Is there some kind of benefits to it? (Or is this just some silly programming style that he was into..?)

This really reminds me a bit of a good way how class member variables can be assigned in the class constructor… something like this:

class MyClass
{
public:
   MyClass(int foo) : mFoo(foo)
   { }

private:
   int   mFoo;
};

instead of this:

class MyClass
{
public:
   MyClass(int foo)
   {
      mFoo = foo; 
   }

private:
   int   mFoo;
};

Answer 1

For basic types there’s no difference. Use whichever is consistent with the existing code and looks more natural to you.

Otherwise,

A a(x);

performs direct initialization, and

A a = x;

performs copy initialization.

The second part is a member initializer list, there’s a bunch of Q&As about it on StackOverflow.