Simple Makefile

At times you may need to test some rather simple code or start a new project. You could just use the commands in the shell which will soon become a pain as you try to clean and recompile the test code. Instead, a build script would be handy.

The files shown below (and associated sources) can be accessed from GitHub https://github.com/cognitivewaves/Simple-Makefile.

Build over simplified

The process of creating native applications/libraries (in C/C++) essentially consists of the following.

  1. Compile each source file (.c or .cpp) to an object file (.o or.obj)
gcc -o test.o -c test.cpp
  1. Link all the object files and dependent libraries
gcc -o test test.o -lstdc++

Makefile

These compilation and link steps can be combined into a “script” called a Makefile for the Make utility.

# Specify compiler
CC=gcc

# Specify linker
LINK=gcc

.PHONY : all
all : app

# Link the object files into a binary
app : main.o
	$(LINK) -o app main.o -lstdc++

# Compile the source files into object files
main.o : main.cpp
	$(CC) -c main.cpp -o main.o

# Clean target
.PHONY : clean
clean :
	rm main.o app

CMakeLists.txt

The CMake toolchain uses a similar concept as Make and has better abstraction. The build steps are saved in CMakeLists.txt (equivalent of Makefile).

cmake_minimum_required (VERSION 2.6)

project (SimpleCMake)

# Compiler flags
set(CMAKE_CXX_FLAGS "-std=c++11")

# Pre-processor definitions
add_definitions()       

# Paths to include files
include_directories()

# Specify binary to be created
add_executable (app main.cpp)

# Paths to dependent libraries
link_directories()

# Specify dependent libraries
target_link_libraries(app stdc++)

Conclusion

As mentioned earlier, this is an extremely simple example. More details can be found at Makefiles and Visual Studio and CMake and Visual Studio, especially if you are coming from a Visual Studio background.

Leave a comment