how to use struct constructor c++ code example

Example 1: c++ struct constructor

struct TestStruct {
        int id;
        TestStruct() : id(42)
        {
        }
};

Example 2: constructor c++ struct

struct Rectangle {
    int width;  // member variable
    int height; // member variable

    // C++ constructors
    Rectangle()
    {
        width = 1;
        height = 1;
    }

    Rectangle( int width_  )
    {
        width = width_;
        height = width_ ;
    }

    Rectangle( int width_ , int height_ )
    {
        width = width_;
        height = height_;
    }
    // ...
};