Re: Ada Strings Libraries for the clueless.

[Simon Wright <simon@pushface.org>]

Caffeine Junky <nospam@hotmail.com> writes:

> Ada.Strings.Fixed
> 
> 	function Index (Source : in String; Pattern : in String;
> 				 Going : in Direction := Forward;
> 				 Mapping : in Maps.Character_Mapping := Maps.Identity)
> 	return Natural;
> 
> 
> Now, the gist of this function is pretty clear. It looks at a String
> and returns the number of how many Characters are in the string(I'm
> assuming.) But what's this "Pattern" string I'm supposed to pass to
> it?  Does it only count the characters in the String that match the
> Pattern given in the Pattern variable?

If you read on to (58) you find

    Each Index function searches for a slice of Source, with length
    Pattern'Length, that matches Pattern with respect to Mapping; the
    parameter Going indicates the direction of the lookup. If Going =
    Forward, then Index returns the smallest index I such that the
    slice of Source starting at I matches Pattern. If Going =
    Backward, then Index returns the largest index I such that the
    slice of Source starting at I matches Pattern. If there is no such
    slice, then 0 is returned. If Pattern is the null string then
    Pattern_Error is propagated.

which seems pretty clear :-)   (except perhaps the Mapping part)