php 根据ping的返回值判断电脑是否在线

<?php 
$key="Request timed out.";
$kkk=array(
    "name3" =>array("192.168.0.118","王五","行政",),
    "name4" =>array("192.168.0.140","李四","财务",),
    "name5" =>array("192.168.0.10","张三","后勤",),
    );

echo "<table border='1' height=50% width=520 cellpadding=0 cellspacing='0' valign='top' bgcolor='#6666FF'>"; 
echo "<th align = 'center'>姓名</th>"; 
echo "<th align = 'center'>部门</th>"; 
echo "<th align = 'center'>状态</th>"; 

foreach ($kkk as $ddd) {
    unset($result);
    exec("ping $ddd[0] -n 1",$result,$rval);

    if ($result[3] == $key){
        echo "<tr> \\n";
        echo "<td align='center'>$ddd[1]</td>";
        echo "<td align='center'>$ddd[2]</td>";
        echo "<td align='center' bgcolor='#000000'><font color='#FF00FF'>离线</font></td>";
        echo "</tr>";
    }else{
        echo "<tr> \\n";
        echo "<td align='center'>$ddd[1]</td>";
        echo "<td align='center'>$ddd[2]</td>";
        echo "<td align='center'><font color='#0033FF'>在线</font></td>";
        echo "</tr>";
    }
}
?>
//该片段来自于http://outofmemory.cn