Ada Programming/Attributes/'First

Description

X'First, where X is any scalar subtype (for example integer, enumerated, real), is an attribute that represents the first value (lower bound) in the range of X.

A'First, where A is an array, denotes the first index value. For more-dimensional arrays, A'First(N) denotes the first index value of the Nth dimension (N must be static).

Example

type My_Enum is (Enum1, Enum2, Enum3);
type My_Int  is range -1 .. 5;
... 
pragma Assert (My_Enum'First = Enum1);   -- OK
pragma Assert (My_Int'First  = -1);      -- OK
pragma Assert (My_Int'First  =  0);      -- Wrong!

See also

Wikibook

• Ada Programming
• Ada Programming/Attributes
• Last
• Range

Ada Reference Manual

• 13.3 Operational and Representation Attributes (Annotated)
• Annex K Language-Defined Attributes (Annotated)