var_dump prints to screen before prepended elements

Question

Why does PHP's var_dump() print fist when I make it the second element of a concatenated string?

echo  "log_files: " . var_dump($log_files);

=> array (size=4)
      0 => string '.' (length=1)
      1 => string '..' (length=2)
      2 => string 'non_ssl_log.txt' (length=35)
      3 => string 'ssl_access_log.txt' (length=31)
   log_files:

And how can I prevent this?

Answer 1

echo "log file : \n";
var_dump($log_files);

as for reason why its doing it no clue sorry.