Increment a filename in PHP

incrementFilename.php

function incrementFilename($filename)
{
	$info = pathinfo($filename);
	$dirname = $info['dirname']=='.' ? '' : $info['dirname'];
	$extension = $info['extension'];
	$basename = basename($info['basename'], '.' . $extension);
	
	
	$arr = explode('_', $basename);
	if(isset($arr[count($arr)-1]) && is_numeric($arr[count($arr)-1]) && count($arr)-1 != 0)
	{
		$arr[count($arr)-1] = (intval($arr[count($arr)-1])+1);
		
		$basename = "";
		$first = true;
		foreach($arr as $val)
		{
			$basename .= (($first)?'' : '_') . $val;
			if($first)
				$first = false;
		}
		return $dirname . '/' . $basename . '.' . $extension;
	}
	else 
	{
		return $dirname . '/' . $basename . '_1.' . $extension;
	}
}