===== System Values =====

'System Values' are special read-only, global variables that provide information about the state of the current player and the world.
e.g.  ''$gPlayerAge'' tells you the age of the current player. Here's a quick example of how you might use that

<code>
  $myvar = $gPlayerAge + 1
  *say Next birthday, %PLAYER% will be $myvar years old
</code>

For a full list of the system values available, see the [[Scripting:Reference:System 
Values|System Values Reference]].

===== System Functions =====

System Functions are used to query the state of a particular aspect of your world where parameters are required to obtain the result. System Functions usually start with **sys**.

For example, to find out how much of a particular item the current player has :

<code>
  $numInInv = sysPlayerInventory( "Wood" )
  *say %PLAYER% is currently carrying $numInInv Wood
</code>

The reference section contains a [[Scripting:Reference:System Functions|full list of System Functions]].

===== System Variables =====

Systems Variables are persistent key/value pairs that you can set and retrieve. There are 3 types :
  * **Server Variables** ( ''$gServerKey[<KEY_NAME>]'' )
  * **Building Variables** ( ''$gBuildingKey[<KEY_NAME>]'' )
  * **Player Variables** ( ''$gPlayerKey[<KEY_NAME>]'' )

**Server** system variables are global (there are one set of values for your world), each constructed building has its own set of **Building** system variables and each player has their own set of **Player** variables.

The ''<KEY_NAME>'' is a case-insensitive, unique identifier for each variable and can be whatever you like. System variables can be set to integer values or text strings, and are referenced using the Key Name as shown :
For example:

<code>
  $gServerKey[Hello] = "Your personalised random number is "
  $gPlayerKey[1] = sysRand( 100 )
  *say Hi %PLAYER%. $gServerKey[Hello] $gPlayerKey[1].
</code>
.. this would print ''Hi [Player_Name]. Your personalised random number is [1-100]''.

Each script event is run in a particular context which determines the building and player variables the script is currently accessing - i.e. When an 'AccessBuilding' event is triggered, the ''$gBuildingKey''s refer to the values set for the particular building being accessed. In some events (e.g. PlayerLogin, UseItem) Building keys are not applicable.

For advanced scripting, you can access building and player system variables by changing the event context using ''SetContext'' and ''SetBuildingContext''.