If : Else : EndIf

If <expression> 
  ...
[ElseIf <expression>]
  ...
[Else]
  ...
EndIf 

The If structure is used to achieve tests, and/or change the programmes direction, depending on whether the test is true or false. ElseIf optional command is used for any number of additional tests if the previous test was not true. The Else optional command is used to execute a part of code, if all previous tests were false. Any number of If structures may be nested together.

Short-circuit evaluations for expressions are supported, meaning if a test is true, all following tests will be ignored and not even run.

Example: Basic test

  a = 5
  If a = 10 
    Debug "a = 10"
  Else
    Debug "a <> 10"
  EndIf    

Example: Multiple test

  b = 15
  If a = 10 And b >= 10 Or c = 20     
    If b = 15
      Debug "b = 15"
    Else       
      Debug "Other possibility"
    EndIf   
  Else     
    Debug "Test failure"
  EndIf  

Example: Short-circuit test

  Procedure DisplayHello()
    Debug "Hello"
    ProcedureReturn 1
  EndProcedure

  a = 10
  If a = 10 Or DisplayHello() = 1 ; a is equal to 10, so the second test is fully ignored
    Debug "Test success"
  Else     
    Debug "Test failure"
  EndIf