Question for Beginners: how to use regular expressions in PHP

Q: How do I use regular expressions in PHP? Preg_replace (& lt; img) (. *) src (S *) & gt ;?, &Quot;%1%2srcimagespo.png lazy-src $3 & quot;, $ data); regular expressions can only be tested correctly in development tools, but cannot be used in PHP. Is it correct to use them? PHP is not proficient. please advise. ------ Q: How do I use regular expressions in PHP?
Preg_replace ('(? ', "$1 $ 2src ='/images/po.png 'lazy-src = $3", $ data );

Regular expressions are only tested correctly in development tools, but cannot take effect in PHP. Is it correct to use them?

PHP is not proficient. please advise.

------ Solution --------------------
Echo preg_replace ('/(? /', "$1 $ 2src ='/images/po.png 'lazy-src = $3", $ data );