Designing Games with Game Maker - YoYo Games

Example
The following program tries to place the current object at a free position (this is about the
same as the action to move an object to a random position).
{
}
do
{
}
x = random(room_width);
y = random(room_height);
until (place_free(x,y))
For statement
A for statement has the form
for ( ; ;)
This works as follows. First statement1 is executed. Then the expression is evaluated. If it is
true, statement 3 is executed; then statement 2 and then the expression is evaluated again.
This continues until the expression is false.
This may sound complicated. You should interpret this as follows. The first statement initializes
the for-loop. The expression tests whether the loop should be ended. Statement2 is the step
statement that goes to the next loop evaluation.
The most common use is to have a counter run through some range.
Example
The following program initializes an array of length 10 with the values 1- 10.
{