komxun / cmake_learn

CMake_Learn

My note from CMake Tutorial

Episode 1 Summarized by Komsun Tamanakijprasart

Table of contents

• makefile
• CMakeLists
  • cmake
• Example 1: Creating a project
• Example 2: Installing your program
• install()

makefile

• Create and name a new file makefile in your working directory
• makefile doesn't accept space, use tab instead

Easy example:

makefile

default:
	g++ main.cpp -o out

You just need to type make in the terminal to execute the makefile (compile and build in this case)

• make to execute the makefile
• ./out to run the application

Linux or Windows terminal

make
./out

Results

CMakeLists.txt

• CMake relies on a top-level file called CMakeLists.txt (exact spelling!)

Project Workflow
Step 1: Prepare your source file main.cpp
Step 2: Create CMakeLists.txt, a separate folder for built files, and run cmake
Step 3: Run make

cmake

2 Important points in CMakeList

• Where your source file is (contain CMakeLists.txt)
• Where your build folder is

Linux terminal

cmake -S <path-to-source> -B <path-to-build>

Ex:

Linux terminal

cmake -S . -B build/

• -S . means the source (and CMakeList.txt) is located in the current directory

Example 1: Creating a Project

Step 1: Prepare main.cpp

CMake_Learn/try_CMakeList/main.cpp

Lines 1 to 7 in eee93c1

	#include <iostream>
	int main()
	{
	std::cout << "Good morning!\n";
	return 0;
	}

Step 2: Create CMakeLists.txt and run cmake

CMakeLists.txt

cmake_minimum_required(VERSION 3.16.3)
project(myProject)
add_executable(${PROJECT_NAME} main.cpp)

What are these lines?

• cmake_minimum(VERSION xxxxx) : Minimum required version
• project(projectName) : Add a project
• add_executable(programName source) : Build the executable file
• ${PROJECT_NAME} : Built-in keyword to refer to the project name

Linux Terminal

cmake -S . -B obj/

Result

• makefile is created along with other files

Step 3: Run make and your program

Linux Terminal - at where the makefile is located

make

Results

Notes:

Check CMake version

Linux terminal

cmake --version

Example 2: Installing your program

Step 1 : Prepare main.cpp

Step 2 : Create CMakeLists.txt and run cmake

CMakeLists.txt

cmake_minimum_required(VERSION 3.16.3)
project(Trim)
add_executable(trim main.cpp)
install(TARGETS targetName DESTINATION bin)

What are these lines?

• install(TARGETS targetName DESTINATION xxx) : specify where to install the executable file (or library), bin is a standard place to install (usually usr/local/bin/)
• Usually, we create a separate folder for the built files (in this case, build)

Linux terminal

cmake -S ..

• -S .. means the source (and CMakeLists.txt) is in the previous directory
• no -B means the current directory is used for build

• Now, in build, the makefile is created and configured along with many other files

Step 3 : run make and your program

Not sure what to make? type make help

install() on CMakeLists.txt

install(TARGETS <targetName> DESTINATION <destination>)

Example:

CMakeLists.txt

cmake_minimum_required(VERSION 3.16.3)
project(Trim)
add_executable(trim main.cpp)
install(TARGETS trim DESTINATION bin)

Install the program, as specified in CMakeLists.txt

Linux terminal

sudo make install

Because we install the program on the bin already, we can call this program ANYWHERE !! (Don't need to locate the program's directory anymore!)