Requirements

• Mac computer
• Xcode installed
• Text editor
• Familiarity with the command line

I'm doing this on a MacBook Pro that I already use for web development. All of the commands and code will be written with that in mind.

Writing the program

Open your terminal and navigate to a directory you want to work in. I made mine in /readingwaters/projects/c-lang-fun

Once there, you'll want to make the file that holds your code. You can do this by running:

touch helloworld.c

Now the file is made open it up in your favorite text editor.

Then put in code that looks like this:

#include <stdio.h>

int main() {
  printf("Hello, World!\n");
  return 0;
}

Lets walk through that line by line

• #include <stdio.h> brings in the header file so we can use printf below
• int main() { sets the return type to integer and defines our main function
• printf("Hello, World!\n"); will print the "Hello, World!\n" string (technically a character array) to standard out, the terminal in our case
• return 0; fulfills our functions return type
• } closes our function

Compiling the program

clang is C compiler that you can use from the command line. There are a ton of them and if you are just starting out, like I am, don't worry about which one too much.

If you have Xcode installed on your Mac, should already have clang. You can check by running:

clang -v

When I run it it gives me:

Apple clang version 15.0.0 (clang-1500.1.0.2.5)
Target: arm64-apple-darwin23.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Do I know what all that means? Nope. It does tell me I have clang installed though 😅

To compile helloworld.c all you have to run is

clang helloworld.c

That should create another file in the same directory called a.out

Running your Hello World program

With helloworld.c compiled to a.out all you need to do is run a.out! You can do this by running:

./a.out

You should get some thing like:

Hello, World!

Huzzah! You did it! A Hello World program in C!