Chapter 2.2 : Hello world with CMake

Let's consider a main.cpp file : 



1
2
3
4
5
6

#include <iostream>

int main(int argc, char** argv){
	std::cout << "Hello World" << std::endl;
	return 0;
}


The CMakeLists.txt file to be used to compile the main.cpp file is :

1
2
3
4

project(HelloWorld)
cmake_minimum_required(VERSION 3.0)

add_executable(hello_world main.cpp)


The structure is simple :

  • Name of the project (basically, what you want).
  • Minimum version of CMake to used the CMakeLists.txt.
  • Create an executable hello_world which uses source file make.cpp


First, go in your project directory and create a build directory :

$ cd my/project
$ mkdir build


Then, the build directory is created :

$ ls
build  CMakeLists.txt  main.cpp


Let's go in the build directory and call CMake :

$ cd build
$ cmake ..


The .. is the path to the parent directory (Where CMake expects a CMakeLists.txt file).


Which gives :

$ cmake ..
-- The C compiler identification is GNU 7.2.0
-- The CXX compiler identification is GNU 7.2.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: XXX/HelloWorldCMake/build


CMake is looking at your compiler automatically.


Then call make :

1
2
3
4
5

$ make
Scanning dependencies of target hello_world
[ 50%] Building CXX object CMakeFiles/hello_world.dir/main.cpp.o
[100%] Linking CXX executable hello_world
[100%] Built target hello_world


Finally, you can call you program : 
$ ./hello_world 
Hello World