Expressions in RoBOTL

An expression is typically made up of operators, variables, integer functions, and boolean functions.

Operators

Operators are used to perform mathematical calculations. For instance, '3 + 4' is made up of the number 3 and 4, and the operator '+' meaning addition.

Valid Operators in RoBOTL (from lowest to highest order of precedence):

Operator Type	Operator	Example(s)
Boolean OR	\|\|, or	variable1 \|\| variable1
Boolean AND	&&, and	variable1 and variable2
Relation	!=, ==	1 != 2
Less-than/Greater-than	<, >, <=,>=	3 > 2
Additional	+, -	3 + 2
Multiplicitive	*, /	8 / 4
Not and Sign	not, !, +, -	-2

Variables

In RoBOTL, Variables are names of locations in which you can store an integer value. Variable names must follow the rules for Names.

Variables occur in both "execute" statements and robot instructions (also called global variables), or in just robot instructions (also called local variables.)

Variables can be used only after being created. You can use the following commands to create a variable for use:

DefineGlobalInteger in the "define" section will create a global variable.
DefineInteger in the "define" section will create a local variable for use within any robot which is a robot type with the variable defined.

Unless given an initial value using one of the above methods, the integer variable will be set by default to a value of 0.

Integer Functions

Integer Functions will return an integer value corresponding to the function.

Function Name	Description	Where Available
BeepersInBag	Returns the number of beepers that the robot has in its beeper bag.	robot instructions
BeepersOnFloor	Returns the number of beepers on the floor in the square the robot is occupying.	robot instructions
XPosition	Returns the current X Position of the robot.	robot instructions
YPosition	Returns the current Y Position of the robot.	robot instructions
MapSize	Returns the order (# of columns/rows) of the current map.	global

Boolean Functions

Boolean Functions will return a true (1) or false (0) value corresponding to the function. Boolean Functions are only valid when used within a robot instruction.

Function Name Description

FrontIsClear/LeftIsClear/RightIsClear Returns false if there is an obsticle (robot or wall) in front/to the left/to the right of the robot.

FacingNorth/FacingSouth/FacingEast/FacingWest Returns true if the robot is facing the declared direction.

Function Name	Description
FrontIsClear/LeftIsClear/RightIsClear	Returns false if there is an obsticle (robot or wall) in front/to the left/to the right of the robot.
FacingNorth/FacingSouth/FacingEast/FacingWest	Returns true if the robot is facing the declared direction.

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Document Last Revised: Tuesday December 16th, 1997 at 2:00am