PHP preg_replace, not replacing right value

Question

The string I am using as my subject is:

'Save 68% on a 4 Day/3 Night vacation at. Only $249!'

I'm using '.\*(\b((enjoy|save)( up to| an extra)?|starting at|as low as|just|only)\b ([0-9]{1,3} ?\%|\$[0-9]+(\.[0-9]{2})?)).\*/i' to try to match a part of the above string a extract it.

I'm using '$1' as the replacement, so my full preg_match looks like

preg_match('.*(\b((enjoy|save)( up to| an extra)?|starting at|as low as|just|only)\b ([0-9]{1,3} ?\%|\$[0-9]+(\.[0-9]{2})?)).*/i', '$1', 'Save 68% on a 4 Day/3 Night vacation at. Only $249!')

It should match 'Save 68%' first but it keeps returning 'Only $249'.

I've found that if I add a question mark after the first wildcard '.\*?(\b((enjoy|save)( up to| an extra)?|starting at|as low as|just|only)\b ([0-9]{1,3} ?\%|\$[0-9]+(\.[0-9]{2})?)).\*/i' it does return 'save 68%'. Is there another way around this. It seems to have to do with my grouping. As I've found that

preg_match('/.*\b(enjoy|save)( up to| an extra)?|starting at|as low as|just|only\b.*/i', '$1', 'Save 68% on a 4 Day/3 Night vacation at. Only $249!')

returns 'save' like it should, but I can't get the same thing to work on the full statement.

Jonah Bishop · Accepted Answer · 2012-10-04 17:49:34Z

1

The reason why adding a question mark after the first wildcard works, is that .* is greedy, and the question mark (.*?) makes it lazy. A greedy operator will match as much as possible, which in your case is the whole line (.* says "match anything as many times as possible"). Making it lazy will cause it to match as little as possible. Read more about this in the repetition section of the PCRE manual pages.

For your particular problem, what's wrong with using the lazy operator? If it results in what you want, I say go with it.

answered Oct 4, 2012 at 17:49

Jonah Bishop

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trickyzter · Accepted Answer · 2012-10-04 17:59:10Z

0

Remove the \b and .* off the start and end of the regular expression. You won't need those, even with a full body of text. See:

http://rubular.com/r/jYjS5WASTw

answered Oct 4, 2012 at 17:59

trickyzter

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Brandon Freitag Over a year ago

Works fine, but I forgot to mention it need to work with mySQL's PREG_REPLACE function as well, which sadly doesn't have all the capabilities found in the PHP version. That was my fault for forgetting to mention that. But otherwise thanks.

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