PHP preg_replace numeric backreference not working

Question

I am trying to wrap numbers inside a given string in a .

$datitle = "hey hey 13";

$datitle = preg_replace('/[0-9]/', '$1', $datitle);

However that returns:

hey hey 

With two empty spans, without the number inside.

What I want to get is:

hey hey 13

How do I use the number matched by preg_replace as a backreference?

u_mulder · Accepted Answer · 2015-12-15 20:24:02Z

2

First of all /[0-9]/ means One number from 0 to 9. This means 1 fits your regexp, 3 fits your regexp. Not 13.

Second - items which are not wrapped in a () are not stored as a result of regexp. But full regexp is stored in $0.

So proper code is:

$datitle = "hey hey 13";
$datitle = preg_replace('/([0-9]+)/', '<span class="title-number">$1</span>', $datitle);
echo $datitle; // hey hey <span class="title-number">13</span>

Or:

$datitle = "hey hey 13";
$datitle = preg_replace('/[0-9]+/', '<span class="title-number">$0</span>', $datitle);
echo $datitle; // hey hey <span class="title-number">13</span>

edited Dec 15, 2015 at 20:24

answered Dec 15, 2015 at 19:59

u_mulder

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