怎么劈开一组数字中的4与7

<br />$strMaxcardid=3655448674;<br />$ar = str_split($strMaxcardid);<br /><br />		foreach($ar as $k => $v) {<br />			<br />    	if ($v == 4 || $v == 7) { <br />           $ar[$v] ++;       <br />            break;    <br />        }}<br />  		$str = join('', $ar);<br />  		echo $str;*/<br />

$strMaxcardid=3655448674;<br />$ar = str_split($strMaxcardid);<br /> <br />foreach($ar as $k => $v) {<br />  if ($v == 4 <br><font color='#FF8000'>------解决思路----------------------</font><br> $v == 7) { <br />    $ar[$k] ++;       <br />  }<br />}<br />$str = join('', $ar);<br />echo $str;