Ada Programming/Attributes/'Pred


Ada Lovelace 1838.jpg

DescriptionEdit

X'Pred(Y) is an Ada attribute where X is any discrete type and Y is a value of that type. This attribute represents the discrete value that has a position number of one less than the input parameter.

The returned discrete value type is the base type of discrete type. If the input parameter is the First value of the discrete type, then a CONSTRAINT_ERROR exception will be raised.

ExampleEdit

type My_Enum is (Enum1, Enum2, Enum3);
...
pragma Assert (My_Enum'Pred (Enum2) = Enum1); -- OK
pragma Assert (My_Enum'Pred (Enum1) = Enum3); -- Wrong

See alsoEdit

WikibookEdit

Ada Reference ManualEdit

Last modified on 5 January 2009, at 23:53