Raspberry Pi Getting started with Raspberry Pi Raspberry Pi Introduction - Hello World in C

Example

Pretext

This is an introduction to the Hello World program example on the Raspberry Pi written in C.
The following example makes use of the command line interface and is set up as a step-by-step guide.
Along with creating a Hello World program, the reader will be introduced to simple linux command line commands.

Note: This introduction was written for beginners.

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Hello World - My first program

First step:
Making a directory that will contain source code.

• Locate your home directory by writing the following command cd
• Make a new folder for your source code mkdir programs
  (Tip: Linux is case sensitive when managing file and directory names)
• Change to your new directory cd programs

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Second step:
Writing your first program.

Linux systems offer a great variety of text editors, natively you will find Vim or Nano.
This example will make use of the Nano text editor.

• Create your source code file nano helloworld.c
• This will open an editor - exiting and saving will create the file in your folder.

The following code is the source code for the Hello World program:

/* My first program */

#include<stdio.h>

int main()
{
   printf("Hello World\n");
}

• After writing the code hit ctrl + x to exit the editor, hit y and then enter to save the changes.
• Write the command ls to check if the file is present in your directory.

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Third step:
Compiling your first program.

• To compile our source code file helloworld.c we need to use a compiler, we will use the
  GNU Compiler Collection - also known as GCC.
• The following command compiles the source code to an executable binary program
  gcc helloworld.c -o myfirstprogram.bin

The source code file is offered as an argument to the GCC compiler and -o defines another argument expressing that we would like the compiler to output something.
In this case we want it to output a .bin file that we named ourselves.

There is several other arguments you can use when compiling with GCC, an example would be
-wall which enables all warnings. This gives you information about any error GCC might encounter.

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Fourth step:
Running your first program.

• Running a program on the Raspberry Pi is done by adding ./ in front of the name of the program that you want to run.
• We can run our program by writing ./myfirstprogram.bin

The command should execute the program and produce Hello World in the console window.