Basic example hello world

00-helloworld.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main(int argc, char** argv) {
+    printf("Hello, world!\n");
+}
+

README.md

@@ -85,3 +85,65 @@ it will get the address of the start of the array `c`, compute the memory addres
 later, and try to see what's there. This will certainly be gibberish and might cause the
 operating system to kill your program.
 
+# Setting Up a Development Environment
+
+To develop C, you need a _compiler_, and it's nice to have a _build system_. I'll assume
+you're on Ubuntu; to install GCC, the GNU Compiler Collection, and make, a build system,
+on Ubuntu, run:
+
+```bash
+sudo apt install gcc make
+```
+
+Now make a directory to work in and open up a file. I'm going to call it `00-helloworld.c`.
+Into that file, type:
+
+```c
+#include <stdio.h>
+
+int main(int argc, char** argv) {
+        printf("Hello, world!\n");
+}
+```
+
+(I'll explain it all in a sec!)
+
+Now, in the terminal, in that folder, type:
+
+```bash
+# GCC, please compile the code in 00-helloworld.c
+# and write the executable out to 00-helloworld.64
+gcc 00-helloworld.c -o 00-helloworld.64
+```
+
+This should print out "Hello, world!" in your terminal. Let's dissect that.
+
+```c
+#include <stdio.h>
+```
+
+Beginning with `#` means that this is a preprocessor directive, telling the compiler
+to look up and include a file called `stdio.h` in the standard search path (because of
+the `<` and `>`, as opposed to `"` and `"` which mean look in the current directory)
+and include its text here.
+
+That file defines, among other things, the function `printf` that is used later.
+
+```c
+int main(int argc, char** argv) {
+```
+
+This is the definition of the magic function `main`, which is run when the program starts.
+It returns an `int`, which should be zero for success or anything else for failure, and
+takes the number of command line arguments `argc` and an array of arrays of characters
+(an array of strings) `argv`. `c` stands for "count" and `v` for "vector" in this case.
+
+```c
+printf("Hello, world!\n");
+```
+
+This calls the `printf` function, which `print`s a `f`ormatted string, although we're
+not using any of the formatting options here.
+
+Congratulations! This is your first C program~
+