帮忙看下怎么会返回null
<?php<br />function newtripos($str,$findstr,$count,$off=0){<br /> $pos=stripos($str,$findstr,$off);<br /> $count--;<br /> if($count>0 && $pos!=false){<br /> $pos=newtripos($str,$findstr,$count,$pos+1);<br /> }else{<br /> var_dump($pos);<br /> return $pos;<br /> }<br />}<br />$a="456123456455654466";<br />$b=newtripos($a,'6',4);<br />var_dump($b);<br />?> 
