strpos function

[mcloan]

Is there a way to use strpos or a similar function to find a location and go backwards to another location. 

i.e. 

11234 Blank St, Houston, TX USA

So starting from $position=strpos($line, "USA") would there be away to find the second comma going back from USA with a strpos or similar function.  I want to prevent from counting character positions if possible.

Thank you.

[taith]

if theres always 2 commas... then this would skip the first...
[code]
$pos=strpos($line,",");
$pos=strpos($line,",",$pos+1);
[/code]

that'll tell you exactly where the 2nd comma is.