Position of compiler flag -l

Question

I\'m currently learning OpenCL. Now, when I want to compile my program, I get an error with this command:

g++ -Wall -l OpenCL main.cpp -o main

Answer 1

With g++ (and generally under Unix), -l specifies a source of input (either a .a or a .so), and input is processed in order. When the input is a static library (a .a file), it will be scanned for objects which resolve undefined references; if it is a .so, there aren't any object files in it, but it will still only be taken into consideration if it resolves some undefined symbol.

When you put the -l before any object files, there are no undefined symbols yet, so nothing will be incorporated into the program.