gsub and slash-ampersand in the substitution string

[Jani Patokallio]

Greetings,

I'm trying to do something that should be very simple: stick a "\" in
front of
every instance of "&" in a string. However, the obvious code...

"this&that".gsub!("&", "*")
--> "this*that" # OK!

"this&that".gsub!("&", "\\&")
--> "this&that" # Wrong

...doesn't work, because "\&" means "last match" in gsub substitution
strings.
How can I escape this? I experimentally determined that entering
"\\\\\\&"
(that's six backslashes) gets the desired result, but I don't really
understand why. Is there a less obscure way of doing this?

Cheers,
-jani

 

[Esteban Manchado Velázquez]

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Greetings,
=20
I'm trying to do something that should be very simple: stick a "\" in=20
front of
every instance of "&" in a string. However, the obvious code...
=20
"this&that".gsub!("&", "*")
--> "this*that" # OK!
=20
"this&that".gsub!("&", "\\&")
--> "this&that" # Wrong
=20
...doesn't work, because "\&" means "last match" in gsub substitution=20
strings.
How can I escape this? I experimentally determined that entering=20
"\\\\\\&"
(that's six backslashes) gets the desired result, but I don't really
understand why. Is there a less obscure way of doing this?

I'm not sure, but I think that the problem is that you are using double
quotes. So, the value you are passing is really the same as:

'\\\&'

Which, once you interpret the escape sequences, you have a literal '\' and a
literal '&'...

--=20
Esteban Manchado Vel=E1zquez <[email protected]> - http://www.foton.es
EuropeSwPatentFree - http://EuropeSwPatentFree.hispalinux.es

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[Jan Svitok]

this was discussed several times, try searching for gsub and \\ or
escaping or something similar. \& is the last match, and \\ is the
whole match. so you need to escape both. The correct solutions to this
'quiz' are posted somewhere, just google it ;-)