如何用其他目录中的依赖项G ++编译.cpp文件

Question

My project is organized the following way:

mainfolder
    |
    |_main.cpp
    |
    |_subfolder
          |
          |_foo.hpp
          |_foo.cpp
          |_bar.hpp
          |_bar.cpp

main.cpp uses functions and variables from foo.hpp and bar.hpp, whose function implementations are in foo.cpp and bar.cpp respectively

I was wondering how I would use g++ to compile main.cpp

Thanks :)

Answer 1

You can compile main on its own like this:

g++ -c main.cpp -Isubfolder -o main.o

This line compiles main.cpp into an object file (not an application) but it gives it the path ( -I<paht> ) where it can fine the include files

You probably want to then also compile the other two files into objects:

g++ -c subfolder/foo.cpp -Isubfolder -o foo.o

g++ -c subfolder/bar.cpp -Isubfolder -o bar.o

Where the -c flag means compile only (and not link). So then you probably want to link your objects together:

g++ main.o foo.o bar.o -o myapp

---

Or in one line:

g++ main.cpp subfolder/foo.cpp subfolder/bar.cpp -Isubfolder -o myapp

The first method (to do it in two steps) is generally easier when you want to create a pattern rule to compile files (with gnu make), the second (in one line) is easier to do manually