regular expression to search word

[frenchy373]

hello
thank you again for your help on regular expression
I check the manual but I don't find how to resolve my new problem:

my text is
"Hello. How are you everybody. Helloword"

I want to find and hightlight "Hello."
with you regular expression :

$str = preg_replace("/\b$keyword\b/", "<b>$0</b>", $str);

result : hightlight nothing"Hello." and "Hellow"

I think that the problem is due to the "." so I try this :

$str = preg_replace("/$keyword/", "<b>$0</b>", $str);

result : hightlight "Hello." and "Hellow"

how can I resolve this?

Thanks again

[laserlight]

The thing is, the period has the meaning "any character"

This means that /Hello./ matches "Hello" followed by 1 other character, any character.
As such,
"Hello." and "Hellow" both match.

You will have to escape the period for the pattern to work right.