Редактирование: SS13 for experienced programmers (раздел)

=== [http://www.byond.com/members/?command=reference&path=proc%2Fif If] ===

Ifs default to checking for true if not otherwise stated. True is defined for all variable types as empty, 0 or non-existant (null).
  if(condition)
    action_true()
  else
    action_false()

==== Common variable behavior in if statements: ====
{|
!Variable type
!False when
!True when
|-
!String (text / ascii)
|"" or null
|Anything else
|-
!Int / Real
|0 or null
|Anything else
|-
!datum, atom
|null
|Anything else
|}

==== [http://www.byond.com/members/?command=reference&path=operator Logical operators] ====
Pretty standard:
  [http://www.byond.com/members/?command=reference&path=operator%2F%21 !statement1] //NOT statement1
  [http://www.byond.com/members/?command=reference&path=operator%2F%26%26 (statement1) && (statement2)] //statement1 AND statement2
  [http://www.byond.com/members/?command=reference&path=operator%2F%7C%7C (statement1) || (statement2)] //statement1 OR statement2
  [http://www.byond.com/members/?command=reference&path=operator%2F%3D%3D ==] //equals
  [http://www.byond.com/members/?command=reference&path=operator%2F%21%3D !=] //not equal
  [http://www.byond.com/members/?command=reference&path=operator%2F%26lt%3B <] ([http://www.byond.com/members/?command=reference&path=operator%2F%26lt%3B%3D <=]) //less (or equal)
  [http://www.byond.com/members/?command=reference&path=operator%2F%26gt%3B >] ([http://www.byond.com/members/?command=reference&path=operator%2F%26gt%3B%3D >=]) //more (or equal)
  [http://www.byond.com/members/?command=reference&path=operator%2F%26 &] //bitflag AND operator. 13 & 3 = 1 (1101 & 0011 = 0001)
  [http://www.byond.com/members/?command=reference&path=operator%2F%7C |] //bitflag OR operator. 13 | 3 = 15 (1101 | 0011 = 1111)

Byond does not recognize the === (identical) operator. More operators can be found in the left menu on the [http://www.byond.com/members/?command=reference&path=operator reference page]