Declaration and Initializations

Universal Initialization

• Brace Initialization: Can be used with any type.

  // do this
  vector <int> vec{4,2};
  // instead of this
  vector <int> vec;
  vec.push_back(4);
  vec.push_back(2);

Advantages

• Narrowing conventions are not allowed.

  int x = 7.7; // legal, only compile warning
  int x{7.7};  // illegal, won't compile

• It is consistent.

  vector <int> old_one(4)    // 0,0,0,0
  vector <int> old_one(4,2) // 2,2,2,2
  vector <int> uni{4}      // 4
  vector <int> uni {4,2}  // 4,2

• Avoids ambiguity.

  Test test(); // object creation or function declaration?
  Test test{}; // object creation!

nullptr

• Literal representing a null pointer.
• It has a special type which is compatible with any pointer type, but cannot be converted to an integer.

  void func(int);
  void func(int *);
  func(nullptr); // calls func(int *) as expected

• The traditional NULL has the value of 0.
• It’s type is implementation defined.

    func(NULL); // Clang: calls func(int *), VC++: calls func(int), GCC: Won't compile