What's the best practice to set html attribute via PHP?

Question

When doing this job in PHP,one may meet this kind of issue:

<span title="<?php echo $variable;?>">... 

The problem is that if $variable contains double quotes,should change it to \"

And that's not the whole story yet:

<span title='<?php echo $variable;?>'>... 

In this case,we need to change single quotes to \',but leave double quotes as is.

So how can we do it in a general property manner?

Answer 1

You always want to HTML-encode things inside HTML attributes, which you can do with htmlspecialchars:

<span title="<?php echo htmlspecialchars($variable); ?>"> 

You probably want to set the second parameter ($quote_style) to ENT_QUOTES.

The only potential risk is that $variable may already be encoded, so you may want to set the last parameter ($double_encode) to false.