    # CStruct Examples
    require 'cstruct'

    # example:
    # struct U in C\C++ (32-bit platform):
    #
    # struct U
    # {
    #    union{
    #       int x;
    #       int y;
    #    }value; /* values is anonymous union's instance */
    # };

    # struct U in Ruby:
    class U < CStruct
        union:value do
            int32:x
            int32:y
        end
    end

    # or like this (use brace):
    # class U < CStruct
    #    union (:position) {
    #        int32:x
    #        int32:y
    #    }
    # end

    # create a U's instance
    u = U.new

    # Notice! Assign is different from C language.
    # 'value' can not be omitted !
    u.value.x = 10

    puts "sizeof(U) = #{U.__size__}" # "__size__" is alias of "size" . You may use 'size'.
    puts "u.value.x = #{u.value.x }, u.value.y = #{u.value.y }"