php - Regex to remove single characters from string

Question

Consider the following strings

breaking out a of a simple prison
this is b moving up
following me is x times better

All strings are lowercased already. I would like to remove any "loose" a-z characters, resulting in:

breaking out of simple prison
this is moving up
following me is times better

Is this possible with a single regex in php?

Answer 1

$str = "breaking out a of a simple prison
this is b moving up
following me is x times better";
$res = preg_replace("@\b[a-z]\b ?@i", "", $str);
echo $res;