Question

In my code i have ints, bools, pointers and so on, i also have some type defined by me with typedef, how can i manage the default value initialization like it happens in the objects with the contrunctor?

I want to be sure that

T var;

if untouched, is always equal to my default value and i like to do this without parsing each line of code anche changing the default value manually and without using a preprocessor macro.

is this possible?
for a new typedef is possible to define a default value?

Answer 1

In C++11, you could write T var{}; to get value initialization to the default value.

In C++03, you could write a non-POD wrapper, whose default constructor will get called by T var;:

template<class T>
struct default_initializer{
  default_initializer() : value() {}
  default_initializer(T const& v) : value(v) {}
  T value;
};

// somewhere in code
default_initializer<T> var; // calls default ctor and initializes 'value'
                            // to its default value

This will allow you to safely default initialize even primitive , POD and aggregate types, which are normally left uninitialized by the T var; declaration.