Create Your First C Program

A simple guide to writing and compiling a C program using gcc and a Makefile.

You will need:

• gcc installed
• make installed
• A terminal

Create a file called main.c:

#include <unistd.h>
 
int main(void) {
    write(1, "Hello, World!\n", 14);
    return 0;
}

To learn about a specific function (like write in this example), you can check the man page — Google: man write or type man write in the terminal.

Now you can turn it into an executable using this command:

gcc -Wall -Wextra -o hello main.c

• -Wall — turn on common warnings
• -Wextra — turn on extra warnings
• -o hello — name the output hello

All the -W* flags are not mandatory for the program to run, but using them is considered best practice.

Run it — it should print something in the terminal:

./hello
Hello, World!

Typing that long gcc command every time gets old fast, so instead, create a Makefile:

CC     = gcc
CFLAGS = -Wall -Wextra
 
all:
	$(CC) $(CFLAGS) -o hello main.c
 
clean:
	rm -f hello

Now just run:

make        # compiles the program
./hello     # runs it
make clean  # deletes the binary

The Makefile is a very powerful and standard tool in low-level programming — worth reading up on as much as you can.

That's it! You wrote a C program, compiled it with gcc, and automated the build with a Makefile.

You might wonder why printf wasn't used here — well, the fun part is that you can reinvent it yourself. That's kind of the whole point. Have fun!