Pike Manual

1.1 Your first Pike program

int main()
{
    write("hello world\n");
    return 0;
}

Let's call this file hello_world.pike, and then we try to run it:

	$ pike hello_world.pike
	hello world
	$

Pretty simple, Let's see what everything means:

int main()

This begins the function main. Before the function name the type of value it returns is declared, in this case int which is the name of the integer number type in Pike. The empty space between the parenthesis indicates that this function takes no arguments. A Pike program has to contain at least one function, the main function. This function is where program execution starts and thus the function from which every other function is called, directly or indirectly. We can say that this function is called by the operating system. Pike is, as many other programming languages, built upon the concept of functions, i.e. what the program does is separated into small portions, or functions, each performing one (perhaps very complex) task. A function declaration consists of certain essential components; the type of the value it will return, the name of the function, the parameters, if any, it takes and the body of the function. A function is also a part of something greater; an object. You can program in Pike without caring about objects, but the programs you write will in fact be objects themselves anyway. Now let's examine the body of main;

{
    write("hello world\n");
    return 0;
}

Within the function body, programming instructions, statements, are grouped together in blocks. A block is a series of statements placed between curly brackets. Every statement has to end in a semicolon. This group of statements will be executed every time the function is called.

write("hello world\n");

The first statement is a call to the builtin function write. This will execute the code in the function write with the arguments as input data. In this case, the constant string hello world\n is sent. Well, not quite. The \n combination corresponds to the newline character. write then writes this string to stdout when executed. Stdout is the standard Unix output channel, usually the screen.

return 0;

This statement exits the function and returns the value zero. Any statements following the return statements will not be executed.