Learn to Use CMake to Compile Code

2018-01-12 by terryoy, in guides

I'm trying to use the Linux environment to develop C/C++ programs, but never really get on the path.

It's not the language that I don't understand, but the environment, the toolchain and how to configure a project in real life is my question. Linux have many programs developed in C/C++, but compiling them myself always out of my scope, which is blocking me from deeper understanding of Linux.

So here I'm reading a walkthrough to help myself making a C/C++ project work.

CMake is said to be an OS and compiler independent build system. So you first write CMake configurations in any source directories, and then it can generate a native build environment that will compile source code, create libraries, generate wrappers and build executables in arbitrary combinations.

0. Build Essential

First of all, if you want to compile anything in Linux, you should install the build-essential package first.

$ sudo apt install build-essential

It contains all the common packages to build Debian packages, such as: g++, gcc, hurd, libc, dpkg, make, etc.

Next step let's install the CMake package:

$ sudo apt install cmake

1. A Hello World and a CMakeLists.txt

The minimal demo has two files.

A hello.cpp source file:

#include <iostream>

using namespace std;

int main(void) {
     cout << "Hello World" << endl;
     return(0);
}

A CMakeLists.txt config file:

# Specify the minimum version for CMake

cmake_minimum_required(VERSION 2.8)

# Project's name
project(hello)

# Set the output folder where your program will be created
set(CMAKE_BINARY_DIR ${CMAKE_SOURCE_DIR}/bin)
set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR})
set(LIBRARY_OUTPUT_PATH ${CMAKE_BINARY_DIR})

# The following folder will be included
include_directories("${PROJECT_SOURCE_DIR}")

# Compile the program to hello
add_executable(hello ${PROJECT_SOURCE_DIR}/hello.cpp)

The three lines cmake_minimum_required, project(hello), and add_executable are essential.

Run below two commands to compile the exectuatble:

# Generate CMake configurations
$ cmake -H. -Bbuild

# Build the executable
$ cmake --build build -- -j3

References

Learning CMake: A Beginner's Guide CMake Official Tutorial