I want to draw a rectangle using a C program. So I was trying to use the graphics.h header. But the GCC compiler gave me a error saying that the library could not be found.
graphics.h is a header that define functions for libbgi (Borland Graphics Interface)
Unless you have a Borland compiler of some sort installed on your Mac (if that's even possible), I think you'll end up having to use other graphic libraries, or install a Windows/Linux Virtual Machine on your Mac and then run/compile your code inside it.