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Ada Programming/Attributes/'Pred

< Ada Programming‎ | Attributes


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.


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

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