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Hi!
Using MSVS 2008, STL TR1 <regex>.

Is there a way to get to know the number of replacements done by
regex_replace(), or at least, whether there was a replacement at all?
Ok, I can compare if(output != input) after regex_replace(), but this is
wasted performance, if there is a better way.

If a regex_error is thrown, how can I get the position of the error in the
regular expression string?

I found that icase (ignore case) only works with A-Za-z, but e.g. not with
German Umlaute (Ää etc.), though I set my German user locale using
regex::imbue(). Am I missing something?

TIA,
Friedel

On 10 mai, 09:23, Friedel Jantzen <nospam_...@freenet.de> wrote:
> Hi!
> Using MSVS 2008, STL TR1 <regex>.
>
> Is there a way to get to know the number of replacements done by
> regex_replace(), or at least, whether there was a replacement at all?
> Ok, I can compare if(output != input) after regex_replace(), but this is
> wasted performance, if there is a better way.

You can roll your own: regex_replace basically instantiate a
regex_iterator from the parameters an performs the replace. It
shouldn't be too hard.

> If a regex_error is thrown, how can I get the position of the error in the
> regular expression string?

AFAIS you cannot; and POSIX regcomp doesn't give more information
either.
You will need a regex format validator.

> I found that icase (ignore case) only works with A-Za-z, but e.g. not with
> German Umlaute (Ää etc.), though I set my German user locale using
> regex::imbue(). Am I missing something?

This may not be implemented or handled correctly by the compiler.

--
Michael

Michael Doubez <> wrote:
> You will need a regex format validator.

You can use a regexp to validate a regexp string. There would be a
marvelous conceptual recursion there...

On 10 mai, 16:47, Juha Nieminen <nos...@thanks.invalid> wrote:
> Michael Doubez <michael.dou...@free.fr> wrote:
> > You will need a regex format validator.
>
> * You can use a regexp to validate a regexp string. There would be a
> marvelous conceptual recursion there...

I hesitated to make the joke but IMO regex grammar is not powerful
enough to validate regex expression.

I actually tried to find one available on the net in C or C++ but,
strangely, none seem readily available (I didn't look too hard, just
googled a bit).

--
Michael

Michael Doubez <> writes:

> On 10 mai, 16:47, Juha Nieminen <nos...@thanks.invalid> wrote:
>> Michael Doubez <michael.dou...@free.fr> wrote:
>> > You will need a regex format validator.
>>
>> Â* You can use a regexp to validate a regexp string. There would be a
>> marvelous conceptual recursion there...
>
> I hesitated to make the joke but IMO regex grammar is not powerful
> enough to validate regex expression.

You're right, regular expression languages are not regular.

-- Alain.

> You can use a regexp to validate a regexp string. There would be a
> marvelous conceptual recursion there...


A homespun validator could possibly not return the same position where the
engine has detected the error.

Friedel

Thank you for your reply!
....
> You can roll your own: regex_replace basically instantiate a
> regex_iterator from the parameters an performs the replace. It
> shouldn't be too hard.

I wrote test code to do this, but as STL regex is new for me, I thought I
could have missed something and reinvent the wheel.
....
> AFAIS you cannot; and POSIX regcomp doesn't give more information
> either.
> You will need a regex format validator.



>> I found that icase (ignore case) only works with A-Za-z, but e.g. not with
>> German Umlaute (Ää etc.), though I set my German user locale using
>> regex::imbue(). Am I missing something?
>
> This may not be implemented or handled correctly by the compiler.

Yes, it looks somehow "premature" to me.

Thank you,
Friedel

On 11 mai, 08:02, Friedel Jantzen <nospam_...@freenet.de> wrote:
> >> I found that icase (ignore case) only works with A-Za-z, but e.g. not with
> >> German Umlaute (Ää etc.), though I set my German user locale using
> >> regex::imbue(). Am I missing something?
>
> > This may not be implemented or handled correctly by the compiler.
>
> Yes, it looks somehow "premature" to me.

You could try toupper/tolower with your local and see if works on the
umlaut (and the eszett ).

--
Michael

Michael Doubez wrote:


> You could try toupper/tolower with your local and see if works on the
> umlaut (and the eszett ).

I was about to tell you that there is no uppercase "ß". But then I
noticed the smiley which made me think that you knew. So I will refrain
from telling you.

Juha Nieminen <> writes:

> Michael Doubez <> wrote:
>> You will need a regex format validator.
>
> You can use a regexp to validate a regexp string. There would be a
> marvelous conceptual recursion there...

Nope, at least not by itself. The language of regexps not itself regular.
I don't know the exact details of TR1 regexps, but I doubt they can
check for matched parentheses.

/L
--
Lasse Reichstein Holst Nielsen
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'