CMake
![cmake logo](https://upload.wikimedia.org/wikipedia/commons/8/8f/Breezeicons-apps-48-cmake.svg)
# Cmake

**Cmake** is a command line tool that can generate building files on practically all platforms (Visual Studio, Xcode, Makefiles, Ninja).

This tutorial will focus on using cmake to generate a **Makefile** for C++ on linux. We assume you have make and cmake installed, or that you would figure how to install them on your own.

## CMakeLists.txt

Let's make a file named CMakeLists.txt and a hello.cpp. Open your terminal and type in this command:

```
touch CMakeLists.txt hello.cpp
```

Now let's code simple hello world program into hello.cpp:

```
#include < iostream >

int main(){
    std::cout << "hello world" << std::endl;
    return 0;
}

```

Then we make a simple CMakeLists.txt code. This code is supposed to tell cmake how to generate the building files.

```
cmake_minimum_required(VERSION 3.0)

project(Hello VERSION 0.0.1 LANGUAGES CXX)

add_executable(hello hello.cpp)
```

Here we have three functions:
- cmake_minimum_required: specify the minimum cmake version required for this CMakeLists to be interpreted correctly.
- project: (project name [version number] [languages used])
- add_executable: (executable name [code sources])

## Run Cmake
We are now going to generare the makefile.

In terminal, go to directory of the files and type:
```
cmake -S . -B builds -G "Unix Makefiles"
```
We had 3 flags in this command:
- S : specify Source / Home directory 
- B : specify Builds directory
- G : type of Generator

We could also omit all flags:
```
cmake .
```
And omitting all flags would produce a Makefile in the current directory.

## Compile With Make

Go to the directory of the Makefile. Type:
```
make
```

Now check your directory:
```
ls
```

There should be a file named **hello**. Execute it as such:
```
./hello
```

It should output:
```
hello world
```

## Compile With Cmake

If we run this command: 
```
cmake --build < builds directory >
```
It will also create the executable inside the builds directory.

This command basically invokes the make command: see above ***Compile With Make*** .

© Paul Caron, aka ChillPill
Cmake Tutorial - Getting Started
