Create the initial command line application

To create a basic Hello World command line application we need to:

Create a directory under the main repository directory like HelloWorld
Create main.cpp file with the C++ source code.
Create a makefile that tells our build system how to compile it
Compile and run it

This is an example main.cpp:

//---------------------------------------------------------------------------
// Copyright (C) 1997-2021 iNTERFACEWARE Inc.  All Rights Reserved
//
// Module: main.cpp
//
// Description:
//
// An example command line app
//
// Author: Eliot Muir
//---------------------------------------------------------------------------

#include <COL/COLostream.h>
#include <stdlib.h>

int main(int argc, const char** argv){
   COLcout << "Hello world!" << newline;
   return EXIT_SUCCESS;
}

The first include COL/COLostream which behaves very similarly to the standard ostream from the standard C++ library. The stdlib.h include gives us EXIT_SUCCESS.

There is a line which prints “Hello World!”.

This is the content of the makefile:

TARGET=HelloWorld

DIRS=\
COL

include ../make/makefile.core

The first line tells the make system to build a command line executable program called HelloWorld
The DIRS variable has the list of libraries that will be compiled and linked together to make the executable.
The include line pulls in the machinery that is required to make the build actually work across the different platforms we work with.