php解决checkbox问题

<script language="javascript" type="text/javascript">

function checkbox()

{

var str=document.getElementsByName("chk");

var objarray=str.length;

var chestr="";

for (i=0;i<objarray;i++)

{

if(str[i].checked == true)

{

chestr+="1";

} else{

chestr+="0";

}

}

document.getElementById("txtcheck").value=chestr;

}

</script>

<tr>

                           <td colspan="4"><table width="100%" cellspacing="0" cellpadding="0">

                               <tr>

                                 <td width="4%" height="25" align="left"><input type="checkbox" value="c1" name="chk" /></td>

                                 <td width="12%" align="left">动力转向</td>

                                 <td width="5%" align="left"><input type="checkbox" value="c2" name="chk" /></td>

                                 <td width="7%" align="left">ABS</td>

                                 <td width="5%" align="left"><input type="checkbox" value="c3" name="chk" /></td>

                                 <td width="11%" align="left">GPS系统</td>

                                 <td width="5%" align="left"><input type="checkbox" value="c4" name="chk" /></td>

                                 <td width="14%" align="left">电动后视镜</td>

                                 <td width="4%" align="left"><input type="checkbox" value="c5" name="chk" /></td>

                                 <td width="16%" align="left">中控/遥控门锁</td>

                                 <td width="4%" align="left"><input type="checkbox" value="c6" name="chk" /></td>

                                 <td width="13%" align="left">手动后视镜</td>

                               </tr>

                               <tr>

                                 <td height="25" align="left"><input type="checkbox" value="c7" name="chk" /></td>

                                 <td align="left">CD</td>

                                 <td align="left"><input type="checkbox" value="c8" name="chk" /></td>

                                 <td align="left">VCD</td>

                                 <td align="left"><input type="checkbox" value="c9" name="chk" /></td>

                                 <td align="left">DVD</td>

                                 <td align="left"><input type="checkbox" value="c10" name="chk" /></td>

                                 <td align="left">车载电话</td>

                                 <td align="left"><input type="checkbox" value="c11" name="chk" /></td>

                                 <td align="left">超视距显示系统</td>

                                 <td align="left"><input type="checkbox" value="c12" name="chk" /></td>

                                 <td align="left">电喷</td>

                               </tr>

                               <tr>

                                 <td height="25" align="left"><input type="checkbox" value="c13" name="chk" /></td>

                                 <td align="left">电动窗</td>

                                 <td align="left"><input type="checkbox" value="c14" name="chk" /></td>

                                 <td align="left">皮椅</td>

                                 <td align="left"><input type="checkbox" value="c15" name="chk" /></td>

                                 <td align="left">布椅</td>

                                 <td align="left"><input type="checkbox" value="c16" name="chk" /></td>

                                 <td align="left">针织座椅</td>

                                 <td align="left"><input type="checkbox" value="c17" name="chk" /></td>

                                 <td align="left">电动椅</td>

                                 <td align="left"><input type="checkbox" value="c18" name="chk" /></td>

                                 <td align="left">化油器</td>

                               </tr>

                               <tr>

                                 <td height="25" align="left"><input type="checkbox" value="c19" name="chk" /></td>

                                 <td align="left">双安全气囊</td>

                                 <td align="left"><input type="checkbox" value="c20" name="chk" /></td>

                                 <td align="left">空调</td>

                                 <td align="left"><input type="checkbox" value="c21" name="chk" /></td>

                                 <td align="left">四轮驱动</td>

                                 <td align="left"><input type="checkbox" value="c22" name="chk" /></td>

                                 <td align="left">巡航定速</td>

                                 <td align="left"><input type="checkbox" value="c23" name="chk" /></td>

                                 <td align="left">天窗</td>

                                 <td align="left"><input type="checkbox" value="c24" name="chk" /></td>

                                 <td align="left">单安全气囊</td>

                               </tr>

                           </table></td>

                         </tr>

代码和内容在同一个页面上