Properly initialising variables in modern C++ (C++11 and above), using () or {}?

Question

The C++ reference pages say that () is for value initialisation, {} is for value and aggregate and list initialisation. So, if I just want value initialisation, which one do

Answer 1

This is my opinion.

When using auto as type specifier, it's cleaner to use:

auto q = p;   // Type of q is same as type of p
auto r = {p}; // Type of r is std::initializer_list<...>

When using explicit type specifier, it's better to use {} instead of ().

int a{};   // Value initialized to 0
int b();   // Declares a function (the most vexing parse)

One could use

int a = 0; // Value initialized to 0

However, the form

int a{};

can be used to value initialize objects of user defined types too. E.g.

struct Foo
{
   int a;
   double b;
};


Foo f1 = 0;  // Not allowed.
Foo f1{};    // Zero initialized.