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Index › Programming Questions & Help › Syntax Questions › Regular Expressions syntax
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Regular Expressions syntax (Read 787 times)
rrrr
Regular Expressions syntax
Feb 27th, 2009, 3:20am  
hi, i'm new to regex's and i can't figure out how to write the syntax to find ONLY the word that follows the word "red" when found in a sentence.

for example, the string "Short red hair and some freckles." should return the word "hair".

my code below returns "red hair and some freckles."
Pattern redwordpattern = Pattern.compile("\\b(red)(.*)", Pattern.CASE_INSENSITIVE);

can someone explain to me why this is? thanks in advance!

i've  been using this as reference:
http://www.shiffman.net/teaching/a2z/regex/#regex
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PhiLho 
Re: Regular Expressions syntax
Reply #1 - Feb 27th, 2009, 8:37am  
String s = "Short red hair and some freckles.";
String[] m = match(s, "\\bred\\s*(\\w+)");
println("Found '" + m[1] + "'");

If you need to include ' and - for example, use:
"\\bred\\s*([\\w'-]+)"
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WWW  
rrrr
Re: Regular Expressions syntax
Reply #2 - Feb 27th, 2009, 9:26am  
thanks!

both
Pattern redwordpattern = Pattern.compile("\\bred\\s*(\\w+)", Pattern.CASE_INSENSITIVE);  
&
Pattern redwordpattern = Pattern.compile("\\bred\\s*([\\w'-]+)", Pattern.CASE_INSENSITIVE);
work.

it's still printing the word "red hair" instead of just "hair". could it be the group() i'm using?

while(redwordmatcherDescrip.find()){
     s+="Description color word:" + redwordmatcherDescrip.group() + newline;
   }


thanks again!
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PhiLho 
Re: Regular Expressions syntax
Reply #3 - Feb 27th, 2009, 12:49pm  
Note I used Processing's match which wraps Pattern and Matcher stuff.

And indeed, group 0 stands for the entire expression while group 1 is the first (and only, here) capture.
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rrrr
Re: Regular Expressions syntax
Reply #4 - Feb 27th, 2009, 8:56pm  
awesome. i didn't know you do matcher and pattern stuff with just "match" in processing. that's cool.

i've been using them separately:

Pattern redpattern = Pattern.compile("\\b(red)\\b", Pattern.CASE_INSENSITIVE);

Matcher redmatcherDescrip = redpattern.matcher(description);

thanks again!
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