Editing Array slicing (section)

===1983: [[Ada (programming language)|Ada 83]] and above===
{{Wikibooks|Ada Programming|Types/array}}
Ada 83 supports slices for all array types. Like [[Fortran#FORTRAN 77|Fortran 77]] such arrays could be passed by <u>reference</u> to another subroutine, the length would also be passed transparently to the subroutine as a kind of '''short''' dope vector.

<syntaxhighlight lang="ada">
with Text_IO;
 
procedure Main is
   Text : String := "ABCDE";
begin
   Text_IO.Put_Line (Text (2 .. 4));
end Main;
</syntaxhighlight>

Produces:
<syntaxhighlight lang="output">
BCD
</syntaxhighlight>

'''Note:''' Since in Ada indices are n-based the term <code>Text (2 .. 4)</code> will result in an Array with the base index of 2.

The definition for <code>Text_IO.Put_Line</code> is:

<syntaxhighlight lang="ada">
package Ada.Text_IO is
   
   procedure Put_Line(Item : in  String);
</syntaxhighlight>

The definition for <code>String</code> is:

<syntaxhighlight lang="ada">
package Standard is

   subtype Positive is Integer range 1 .. Integer'Last;

   type String is array(Positive range <>) of Character;
   pragma Pack(String);
</syntaxhighlight>

As Ada supports true negative indices as in {{code|type History_Data_Array is array (-6000 .. 2010) of History_Data;|ada}} it places no special meaning on negative indices. In the example above the term <code> Some_History_Data (-30 .. 30)</code> would slice the <code>History_Data</code> from 31 [[Before Christ|BC]] to 30 [[Anno Domini|AD]] (since there was no year zero, the year number 0 actually refers to 1 [[Before Christ|BC]]).