Strange narrowing conversion error from FLTK Color to Color Struct, Stroustrup's header Graph.h
Recently i have reached the chapter concerning Graphics in Stroustrup's book PPP2 , however i have faced unsettling _narrowing conversion_ error in Graph.h line 159 , after building and configuring the FLTK 1.1.10 library, the headers _dependant on FLTK_ provided by Stroustrup are in this Git Repo: https://github.com/MackSix/ppp-stroustrup.git . I have spent days trying to find a solution ,but so far i had no luck, i have searched the Web and posted the problem on StackExchange but no one has offered any solution, I have stopped coding completely because of this problem. The source code for the program is_ i use visual studio 2022 community with C++ 14 Standard : #include"../std_lib_facilities.h" #include "../Simple_window.h" #include "../Graph.h" int main() { using namespace Graph_lib; Point tl{ 100,100 }; // our graphics facilities are in Graph_lib // to become top left corner of window Simple_window win{ tl,600,400,"Canvas" }; // make a simple window Polygon poly; poly.add(Point{ 300,200 }); poly.add(Point{ 350,100 }); poly.add(Point{ 400,200 }); poly.set_color(Color::red); win.attach(poly); win.wait_for_button(); } The error message provided by the compiler is: Error C2397 conversion from 'Fl_Color' to 'unsigned long' requires a narrowing conversion pain C:\Users\abdua\source\repos\Graph.h 159 Any help would be much appreciated. Thank you in advance .