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Uniform Initialization | C++ 11


C++ 03 : 

 class Dog {     // Aggregate class or struct
   public:
      int age;
      string name;
};
Dog d1 = {5, "Henry"};   // Aggregate Initialization


Uniform Initialization:

 Uniform Initialization expands on the Initializer List syntax, to provide a syntax that allows for fully uniform type initialization that works on any object – removing the distinction between initialization of aggregate + non-aggregate classes, arrays, STL/custom collection classes, and PODs.
// C++ 11 extended the scope of curly brace initialization
class Dog {
   public:
      Dog(int age, string name) {...};
};
Dog d1 = {5, "Henry"}; 


 Uniform Initialization Search Order:
1. Initializer_list constructor
2. Regular constructor that takes the appropriate parameters.
3. Aggregate initializer.


==> Dog d1{3};

 Example:

 class Dog {
   public:
   int age;                                // 3rd choice

    Dog(int a) {                            // 2nd choice
      age = a;
   }

    Dog(const initializer_list& vec) { // 1st choice
      age = *(vec.begin());      
   }
};
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