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c++default-constructor

Is it possible to make a C++ type that mimics the constructor semantics of fundamental types?

The constructor semantics of int/double/etc. are:

int a; // uninitialized
int b = int(); // zero initialized
int c = int(4); // four

Is it possible to define a class with exactly the same behavior? I.e., one that has both uninitialized and initialized default constructors? I believe this is impossible, and currently work around it by making a constructor that compiles only when called with 0, but want to make sure there isn't a way to exactly mimic fundamental types.

Solution

  • If no constructors defined:

    struct A { int x; };

A a; // default-initialized (unintialized)
A b = A(); // value-initialized
A c = { 4 }; // four