cmake Getting started with cmake Simple "Hello World" Project
Example
Given a C++ source file main.cpp defining a main() function, an accompanying CMakeLists.txt file (with the following content) will instruct CMake to generate the appropriate build instructions for the current system and default C++ compiler.
main.cpp (C++ Hello World Example)
#include <iostream>
int main()
{
std::cout << "Hello World!\n";
return 0;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.4)
project(hello_world)
add_executable(app main.cpp)
-
cmake_minimum_required(VERSION 2.4)sets a minimum CMake version required to evaluate the current script. -
project(hello_world)starts a new CMake project. This will trigger a lot of internal CMake logic, especially the detection of the default C and C++ compiler. -
With
add_executable(app main.cpp)a build targetappis created, which will invoke the configured compiler with some default flags for the current setting to compile an executableappfrom the given source filemain.cpp.
Command Line (In-Source-Build, not recommended)
> cmake .
...
> cmake --build .
cmake . does the compiler detection, evaluates the CMakeLists.txt in the given . directory and generates the build environment in the current working directory.
The cmake --build . command is an abstraction for the necessary build/make call.
Command Line (Out-of-Source, recommended)
To keep your source code clean from any build artifacts you should do "out-of-source" builds.
> mkdir build
> cd build
> cmake ..
> cmake --build .
Or CMake can also abstract your platforms shell's basic commands from above's example:
> cmake -E make_directory build
> cmake -E chdir build cmake ..
> cmake --build build
