OldSchoolCode

A c program consists of functions, each function is a block of code which can be executed over and over again. The compiler looks for a special starting function when compiling your program, this function is called "main". Every function is enclosed by curly braces {}.your first "main" should look like this:

void main( void )
{

}

So, what do the words 'void' mean? The first 'void' is what type of data the function will return, the second 'void' is what type of data the function will accept. Both of these will be explained later, all you need to know now is void means "no data". Essentially we're telling the compiler this function will accept and return no data.

Our next function is called printf. It has already been written for us and allows us to print text to the output window. This function exists in a file called stdio.h (Standard Output). The first thing to do in our program is to tell the compiler we might want to use any functions in stdio.h

//#include is a preprocesser directive
//in layspeak, it tells the compiler to do
//something before compiling our code
//in this case we're telling it to include
//all the code written in the file stdio.h
#include <stdio.h>

//now we start our program
void main( void )
{
   printf( "Hello World!" );
}

That's it, your first program! Remember when I said a function can accept data? printf accepts data as an array of characters (called a string) we pass it this data inside of paranthesis...which is our "Hello World".

If you're using Windows and not running in Visual Studio, the program probably runs and disappears too fast. In the next tutorial we'll show you how to pause the screen.But for now you'll have to run it from a DOS prompt or run it inside the Visual Studio Debugger (the play button in Visual Studio).