Replacing with backrefs does not work, can anybody explain why?

[Val Starovoitov <va...@picknowl.com.au>]

Hi, 
probably it is a question to developers:

Backrefs work fine in the search string, but do not work in replace string.

Example1 
(in replace - does not work):

new RE( "(..)ple").subst ( "Apple is tasty", "\\1ricot");
Returns:             "\1ricot is tasty"
My expectation:   "Apricot is tasty"


Example2 
(in search - does work):
new RE( "(.)=\\1").subst ( "0=0 is correct", "1=1");
Returns:             "1=1 is correct"

Regards,
Val Starovoitov.

Re: Replacing with backrefs does not work, can anybody explain why?

[Val Starovoitov <va...@picknowl.com.au>]

Hi, Schamil,
replacement of "\\1" to "\1" does not work because:
1) I have tried that and it produced a replace string like: "?ricot" with symbol with ASCII code 1, as it supposed to be.
2) If RE understands "\\1" in the 2nd example in search string, then it was done OK and should work in the 1st example. 

These are examples from my 1st letter:
Example1 
(in replace - does not work):
new RE( "(..)ple").subst ( "Apple is tasty", "\\1ricot");
Returns:             "\1ricot is tasty"
My expectation:   "Apricot is tasty"

Example2 
(in search - does work):
new RE( "(.)=\\1").subst ( "0=0 is correct", "1=1");
Returns:             "1=1 is correct"

Cheers,
Val.

----- Original Message ----- 
From: "Schamil Wackenhut" <sw...@wacke.org>
To: "Regexp Users List" <re...@jakarta.apache.org>; "Val Starovoitov" <va...@picknowl.com.au>
Sent: Thursday, June 05, 2003 18:11
Subject: Re: Replacing with backrefs does not work, can anybody explain why?


> * Val Starovoitov meinte:
> 
> > new RE( "(..)ple").subst ( "Apple is tasty", "\\1ricot");
> > Returns:             "\1ricot is tasty"
> > My expectation:   "Apricot is tasty"
> 
> Try \1ricot. The problem is you escape the second backslash
> instead of 1.
> -- 
> /earth: file system full.
> 
> 
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> 

Re: Replacing with backrefs does not work, can anybody explain why?

[Schamil Wackenhut <sw...@wacke.org>]

* Val Starovoitov meinte:

> new RE( "(..)ple").subst ( "Apple is tasty", "\\1ricot");
> Returns:             "\1ricot is tasty"
> My expectation:   "Apricot is tasty"

Try \1ricot. The problem is you escape the second backslash
instead of 1.
-- 
/earth: file system full.


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