出典:Wikipedia
出典:『Wikipedia』 (2010/09/24 01:11 UTC 版)
In computing (particularly, in programming), undefined value is a condition where an expression has not a correct value, although it is syntactically correct. Undefined value may not be confused with empty string, boolean "false" or other "empty" (but defined) values. Depending on circumstances, evaluation to undefined value may lead to exception or undefined behaviour, but in some programming languages undefined values can occur during a normal, predictable course of program execution.