Manjaro Linux cannot open source file "gtkmm.h" - c++

Question

I have been trying to set up my coding environment for GUI development in c++ recently, with little success. I use Manjaro Linux with Visual Studio Code, but for some reason, I always seem to get include errors when including files that I know are there.
Most recently, I tried to set up gtkmm-4.0 by installing the package and the documentation. I double checked in /usr/include/ to ensure the packages were all present, but I still am getting include errors:
cannot open source file "gtkmm.h" and
gtkmm.h:No such file or directory
At this point, all the code I have is:
#include <gtkmm.h>
#include <iostream>
int main(int argc, char* argv[]){
return 0;
}
Makefile:
exec = game.out
sources = $(wildcard src/*.cpp)
objects = $(sources:.cpp=.o)
flags = -g $(shell pkg-config gtkmm-4.0 --cflags)
libs = $(shell pkg-config gtkmm-4.0 --libs)
$(exec): $(objects)
g++ $(objects) $(flags) -o $(exec) $(libs)
%.o: %.cpp include/%.h
g++ -c $(flags) $< -o $#
install:
make
cp ./game.out /usr/local/bin/game
clean:
-rm *.out
-rm *.o
-rm src/*.o
I have scoured the internet for answers, but everything I found was either for a different os/environment or just didn't
#Galik and #John helped me solve this!
What I had to do was use g++ src/main.cpp -o main $(pkg-config gtkmm-4.0 --cflags --libs) to compile my code, then run the executable.
Thank you both for your help and guidance!!

Answer 1

You need to install pkg-configand add this to the compiler flags in your Makefile:
flags = -g $(shell pkg-config gtkmm-2.4 --cflags)
libs = $(shell pkg-config gtkmm-2.4 --libs)
# ...
$(exec): $(objects)
g++ $(objects) $(flags) -o $(exec) $(libs)
The tool pkg-config has a database of the correct paths for supporting libraries.
Depending on your version if gtkmm, you may need to substitute gtkmm-3.0, if you have version 3.0.