ILOG OPL Development Studio Language Reference Manual

Automatic conversion to BooleanWhen a function, method or statement which expects a Boolean value as one of its argumentsis passed a non-Boolean value, this value is automatically converted to a Boolean value asfollows:♦The number 0 yields false.♦The empty string "" yields false.♦The null value yields false.♦The undefined value yields false.♦Any other non-Boolean values yield true.For example:"The 10 commandments".indexOf(10) -> 4"The " + 10 + " commandments" -> "The 10 commandments"if ("") writeln("True"); else writeln("False");if (123) writeln("True"); else writeln("False");This displays “False”, then “True”.I 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 L233