ILOG OPL Development Studio Language Reference Manual

The undefined valueThe undefined value is a special value used in some places to specify an absence of information.For example, accessing a property of a value which is not defined, or a local variable whichhas been declared but not initialized, yields the undefined value.There is no way of referencing the undefined value in programs. Checking if a value is theundefined value can be done using the typeof operator:typeof(value) == "undefined" -> true if value is undefined,false otherwise.Methods of undefinedThere is only one method of undefined.Methods of undefinedSyntaxEffectundefined.toString() Returns the string "undefined".260I L O G O P L D E V E L O P M E N T S T U D I O L A N G U A G ER E F E R E N C E M A N U A L