For

The most complex loop is the for statement, for all of its configurations.

for (<assignment>; <expression>; <modifier>)

There are things to be said about each of these parts, so let’s break it down:

for loop component	description	example
<assignment>	declares the starting value of the variable the loop is using	i=1
<expression>	the code block will execute as long as this expression is true	i <= 15
<modifier>	change to the variable after every iteration of the loop	i++

Let’s look at this code for the bat in HugoZork:

     local i
     for (i=0; i<3; i++)
     {
     "_   Fweep!"
     }

Which results in:

`  Fweep!   Fweep!   Fweep!`

Defining By Omission

The for loop will still work if one of the components mentioned above is missing. Depending on which one, the resulting loop will perform in different ways.

omission type	how it is processed
for (; i<4 ; i++)	A missing assignment results in the loop starting with the value of the variable (“i” in this case) being whatever it was before the loop. Of course, if the variable is a recently-defined local variable that hasn’t been given a value yet, that means it’ll be starting at 0.
for (i=1;;i++)	If there isn’t an declared, the loop will execute indefinitely. This means that the code block must execute [break](guts/break/) under some circumstances.
for (i=1; i<4 ;)	(Yes, that last semi-colon is necessary) This case requires the code block to break under certain circumstances or change the value of the variable itself to avoid an endless loop, but other than that, it will still run fine.

Consecutively defined objects

If you have several objects that are defined together for which the same action will be applied to, you can take advantage of the fact that each of their object numbers will be consecutive, too. Let’s pretend that your game has a toy chest and the protagonist automatically puts toys back in the chest when leaving the room, you could do something like this:

for (x=first_toy ; x<=last_toy ; x++)
{
	move x to toy_chest
}

for x in object

The other way that for can be used is for executing code against every object within another object.

This executes the code block with the first child of the object as the variable. It then executes again with the next child (and so on).

Note:

It’s important to remember that if the “x” is moved out of the object within the code block, once it gets to the end of the code, it will stop there (skipping any remaining objects).