preg_replace conditional replacement with different string

Question

I know there's a if/then in the matching of regular expressions, but is there one in the replace?

ie. I want to do in one regex

"I have Foo Bars under $5 for sale" to be "Foo Bars~$5"

"I have Foo Bars for sale" to become "Foo Bars" and NOT "Foo Bars~"

I have an expression a bit like this at the moment:

preg_replace("/(([A-Z][a-z]*\s){1,3})((under .)\d+)?/","$1~$4",$str);

(with other bits to remove the other text aswell of course!) but that includes the ~ even when there's no 'under' in it.

I could probably use preg_replace_callback but that seems a bit OTT

Thanks.

Why not compare the strings in php then have different preg_replace expressions for them? I don't understand the why you're searching for a complicated way to solve a simple solution. — theAlexPoon
– theAlexPoon, Commented Oct 19, 2010 at 16:05
Yes, in my example I could do that, but what I'm trying to do involves parsing a page of text and I'd quite like to get it done in one regexp if possible — Vortigern
– Vortigern, Commented Oct 20, 2010 at 7:28

Simon · Accepted Answer · 2010-10-19 23:03:41Z

2

Php's trim function would do:

// Before: "Foo Bars~$5"
    $str = trim($str,'~');
// After: "Foo Bars~$5"

// Before: "Foo Bars~"
$str = trim($str,'~');
// After: "Foo Bars"

answered Oct 19, 2010 at 23:03

Simon

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