What does the Global Variable $s represent?

Question

What does the $GLOBALS['s'] variable contain? It looks like an empty array, but what would it normally hold?

I've encountered it in a tutorial: The WordPress Theme: Single Post, Post Attachment, & 404 Templates, it mentions a long string that gets passed to a printf function call.

The string looks something like this:

//START OF STRING

$entry_utility = <<<LONGSTR
This entry was posted in %1{$s}%2{$s}.
Bookmark the <a href="%3{$s}" title="Permalink to %4{$s}" rel="bookmark">permalink</a>.
Follow any comments here with the
<a href="%5{$s}" title="Comments RSS to %4{$s}" rel="alternate" type="application/rss+xml">RSS feed for this post</a>.
LONGSTR;

//END OF STRING

NOTE: I've wrapped the long string from the tutorial inside a HEREDOC string instead, it was too hard to follow on the single line.

I've wrapped the $s variables in curly-brackets in case heredocs couldn't interpret them correctly.

Answer 1

It's not a global variable; in fact it's not a variable at all. It's just placeholder within the sprintf() function. Take a look at the sprintf PHP function documentation.

In the example you cite, the author is using the 'argument swapping' placeholder syntax: %n$t where %n is the placeholder number that corresponds to the argument order (eg: %1, %2 etc) and $t is the type indicator, where 't' is one of 's', 'd', 'f' etc (eg: $s, $d etc). Put them together and you get %1$s %2$d etc.