Trouble escaping regex strings

[Xx r3negade]

I'm using regular expressions to parse HTML hyperlinks and I've run into a problem. I'm trying to escape characters
such as '.' and '?' for use in regular expressions, but it's not working

# Grabs a link.  For this example, let's say that the string grabbed is '<a href="http://google.com/?q=foo">Click</a>'
link_url_original = GetLink()
 
# Sanitize string for regex use
link_url_original = re.sub("\.", "\.", link_url_original)
link_url_original = re.sub("\?", "\?", link_url_original)
 
toSub = 'http://google.com/?q=foo'
to Repl = 'http://www.yahoo.com'
 
final = re.sub(toSub, toRpl, link_url_original)
print final
 

The output is:

<a href="http://google\.com/\?q=foo">Click</a>

Why aren't the added slashes being interpretted as escape characters?

[Das123]

The regular expression is the match string, not the replace string. The correct syntax would be like

result = re.sub("\.", ".", subject)

[Xx r3negade]

The regular expression is the match string, not the replace string. The correct syntax would be like

result = re.sub("\.", ".", subject)

Replace a "." with another "."? What???

[Das123]

Ahh, sorry. I didn't understand what you were trying to do.

The answer is that the toSub needs to be escaped, not the link_original_url...

import re
#link_url_original = GetLink()
link_url_original = '<a href="http://google.com/?q=foo">Click</a>'
 
toSub = "http://google.com/?q=foo"
# Sanitize string for regex use
toSub = re.sub("\.", "\.", toSub)
toSub = re.sub("\?", "\?", toSub)
toRpl = "http://www.yahoo.com"
 
final = re.sub(toSub, toRpl, link_url_original)
print final
 

The result is...

<a href="http://www.yahoo.com">Click</a>

[Xx r3negade]

Ah, I can't believe I didn't catch that, thanks.