Extraction of strings

There is a string:

<code class="php">$content="1+ssdsddss";</code>

Please tell me how to use the php string function to extract "1+", thank you. (Beginners, please answer patiently, thank you)

Reply content:

There is a string:

<code class="php">$content="1+ssdsddss";</code>

Please tell me how to use the php string function to extract "1+", thank you. (Beginners, please answer patiently, thank you)

$str = substr($content,2);