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Re: string-match bug?


From: David Kastrup
Subject: Re: string-match bug?
Date: Mon, 14 Dec 2009 14:53:21 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.50 (gnu/linux)

Andreas Röhler <address@hidden> writes:

> Matthew Dempsky wrote:
>> On Mon, Dec 7, 2009 at 12:37 PM, Andreas Röhler
>> <address@hidden> wrote:
>>> Why should questioned string respond here it contains an empty string at 
>>> position 0?
>>> Makes no sense for me.
>> 
>> Here's an analogy: (string-match "xyzzy" "fooxyzzybar") returns 3.
>> This is because the first 5 characters starting at position 3 are
>> "xyzzy", the same as the first string parameter.  The significance of
>> 5 here is the length of "xyzzy".
>> 
>
> Well, string-match should tell first point of occurrence if any.
> If we have none, as with slightly changed example
>
> (string-match "xyzzy" "foox-a-yzzybar")
> it duly returns "nil"  - and not "0" saying falsly "first point of 
> non-occurence"
>
>
> (string-match "" "fooxyzzybar") asks, if there is an empty string in string.
> If yes, report the starting point of the empty string.
>
> Does string start with an empty string? IMHO not.

(concat "" "fooxyzzybar") -> "fooxyzzybar", so obviously the empty
string starts of the resulting string "fooxyzzybar".

-- 
David Kastrup


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