Strange behaviour with str_ireplace()

Hi all. I found some unexpected behaviour with str_ireplace. To summarize, if the $replace term is a number, but formatted as currency with trailing zero's (34.50) the function drops the trailing zero. Example : $price=34.5; $message="You owe me #amount#."; $message1 = str_ireplace("#amount#,sprintf("%01.2f",$price),$message); $message2 = str_ireplace("#amount#,"$".sprintf("%01.2f",$price),$message); $message1 will yield "You owe me 34.4" $message2 will yield "You owe me $34.40" So in other words, if the replace term can be interpreted as a number, it will be, including truncation of zero's. I didn't expect this, because as the function name suggests, it's a *string* replace. Fortunately I can just add a $ to the amount and make it work as a string, not a number but this would not always be the case. Is this by design, or is it a bug?