Compilation

Before we can run this program we need to compile it. This will produce the actual executable we can run on our computer. Open up the command line and browse to the directory that hello_world.c is saved in. You can then compile your program using the following command.

cc -std=c99 -Wall hello_world.c -o hello_world

This compiles the code in hello_world.c, reporting any warnings, and outputs the program to a new file called hello_world. We use the -std=c99 flag to tell the compiler which version or standard of C we are programming with. This lets the compiler ensure our code is standardised, so that people with different operating systems or compilers will be able to use our code.

If successful you should see the output file in the current directory. This can be run by typing ./hello_world (or just hello_world on Windows). If everything is correct you should see a friendly Hello, world! message appear.

Congratulations! You’ve just compiled and run your first C program.