1. User-defined data types

• In C, the structures are introduced by the struct keyword.

• The struct aggeregates data members into a single object.

• The struct can be used as a user-defined data type:

  
  #include <iostream>
  
  struct Rectangle {
      int width;  // member variable
      int height; // member variable
  };
  
  int main()
  {
      Rectangle rect { 20, 10 };
      std::cout << "rectangle width: " << rect.width << '\n';
      std::cout << "rectangle height: " << rect.height << '\n';
      return 0;
  }
  
  

• In this sample, the rect is an object. This object is the result of instantiation of the struct Rectangle.