Question

Very basic, but would like to know the difference/security ramifications etc of using ” vs. ‘.

Can someone provide an example that explains when to use each one?

Answer 1

There are a lot of subtle differences, you’ll want to read the php documentation to get a lot of the details, but the important detail are:

Double quotes are parsed whereas single quotes are literals.

You can use variables inline with double quotes, but not with single quotes.

There are some catches though:

<?php
$beer = 'Heineken';
echo "$beer's taste is great"; // works; "'" is an invalid character for variable names
echo "He drank some $beers";   // won't work; 's' is a valid character for variable names but the variable is "$beer"
echo "He drank some ${beer}s"; // works
echo "He drank some {$beer}s"; // works
?>

Single quotes are slightly faster.