为什么这个正则表达式不返回任何东西？

Question

preg_match_all('/<p>.*:</p>/gm', $content, $matches);
var_dump($matches); //ouput is NULL

I want something like this: <p>The Ideal Candidate:</p> to match but not <p>Some more text</p> . The requirement being it must contain a <p> tag followed by some text and at the end it must contain a : followd by the end of the p tag ( </p> ).

Note: I tried escaping the ending p tag, but it is still not working. Updated code:

preg_match_all('/<p>.*:<\/p>/gm', "<p>The Ideal Candidate:</p>", $matches);

Answer 1

Escape the / or use another delimiter

 /<p>(.*?:)<\/p>/m

or

 #<p>(.*?:)</p>#m

Tested:

preg_match_all('#<p>(.*?:)</p>#m', "<p>The Ideal Candidate:</p>", $m);
print_r($m)

output:

Array
(
    [0] => Array
        (
            [0] => <p>The Ideal Candidate:</p>
        )

    [1] => Array
        (
            [0] => The Ideal Candidate:
        )

)

Answer 2

g is not a valid modifier, see PHP: Pattern modifiers . You should pay close attention to the warnings PHP issue. When running

preg_match_all("/<p>.*:<\/p>/gm", "<p>The Ideal Candidate:</p>", $matches);
print_r($matches);

I get

Warning: preg_match_all() : Unknown modifier ' g ' in Command line code on line 1

Whereas the same line without the g modifier yields

Array
(
    [0] => Array
        (
            [0] => <p>The Ideal Candidate:</p>
        )
)