Xcode 4 FLTK 1.3.0 undefined architecture x86_64-Collection of common programming errors

Hi, I am using Xcode 4 and trying to set up FLTK 1.3.0 to run Bjarne Stroustrup’s Chapter 12 FLTK Demo at the end of the chapter. I keep getting the following error when compiling, and have no idea where to go. I have an idea it might have to do with the linker flags, but I don’t know what flag to add and where…

Here’s the error:

Undefined symbols for architecture x86_64: “Fl_JPEG_Image::Fl_JPEG_Image(char const*)”, referenced from: Graph_lib::Image::Image(Point, String, Graph_lib::Suffix::Encoding) in Graph.o “Fl_GIF_Image::Fl_GIF_Image(char const*)”, referenced from: Graph_lib::Image::Image(Point, String, Graph_lib::Suffix::Encoding) in Graph.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Originally posted 2013-11-09 22:56:21.