function CheckForm()
{
 var numbers = "0123456789";

 if (document.advsearch.byyear.value!="")
 {
  for (i=0; i< document.advsearch.byyear.value.length; i++){
     var CheckChar = document.advsearch.byyear.value.charAt(i);
     if (numbers.indexOf(CheckChar) == -1){
       alert("毕业日期格式不正确！");
       document.advsearch.byyear.focus();
       return false;
      }
    }
 }

 if (document.advsearch.zdnl.value!="")
 {
  for (i=0; i< document.advsearch.zdnl.value.length; i++){
     var CheckChar = document.advsearch.zdnl.value.charAt(i);
     if (numbers.indexOf(CheckChar) == -1){
       alert("年龄格式不正确！");
       document.advsearch.zdnl.focus();
       return false;
      }
    }
 }

 if (document.advsearch.zxnl.value!="")
 {
  for (i=0; i< document.advsearch.zxnl.value.length; i++){
     var CheckChar = document.advsearch.zxnl.value.charAt(i);
     if (numbers.indexOf(CheckChar) == -1){
       alert("年龄格式不正确！");
       document.advsearch.zxnl.focus();
       return false;
      }
    }
 }


 
 else
   return true
}