Regular Expressions 101

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/
(?<=>)[\+\-]?\d+\.?\d*(?=<)
/
g
Positive Lookbehind
(?<=>)
Assert that the Regex below matches
> matches the character > with index 6210 (3E16 or 768) literally (case sensitive)
Match a single character present in the list below
[\+\-]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\.
matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\d
matches a digit (equivalent to [0-9])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Positive Lookahead
(?=<)
Assert that the Regex below matches
< matches the character < with index 6010 (3C16 or 748) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String

Code Generator

Generated Code

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Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php