<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> 简单计算器</TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<script language="JavaScript">
      var m=0;
     //是第一操作数
      function SetExp(str){
      if(m==1)
   //根据m值判定结果是否为第一操作数
      {
   document.Nform.result.value="";
           m=0;
      }
      else(m==0)
      {
  document.Nform.result.value+=str;
      }
      }
      function Cal(result){
      var str=document.Nform.result.value;
      document.Nform.result.value=eval(str);
      m=1;
      }
      function Clear(){
      document.Nform.result.value="";
      }
</script>
</HEAD>
<BODY>
<center>
<h2></h2>
<form name=Nform method=get>
<table border="1" bordercolor="#003300">
<tr>
     <td colspan="3">
           <input type=text name="result">
     </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="1" onClick="SetExp('1')">
    </td>
     <td>
           <input type="button" value="2" onClick="SetExp('2')">
    </td>
     <td>
           <input type="button" value="3" onClick="SetExp('3')">
    </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="4" onClick="SetExp('4')">
    </td>
     <td>
           <input type="button" value="5" onClick="SetExp('5')">
    </td>
     <td>
           <input type="button" value="6" onClick="SetExp('6')">
    </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="7" onClick="SetExp('7')">
    </td>
     <td>
           <input type="button" value="8" onClick="SetExp('8')">
    </td>
     <td>
           <input type="button" value="9" onClick="SetExp('9')">
    </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="0" onClick="SetExp('0')">
    </td>
     <td>
           <input type="button" value="." onClick="SetExp('.')">
    </td>
     <td>
           <input type="button" value="C" onClick="Clear()">
    </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="+" onClick="SetExp('+')">
    </td>
     <td>
           <input type="button" value="-" onClick="SetExp('-')">
    </td>
     <td>
           <input type="button" value="*" onClick="SetExp('*')">
    </td>
</tr>
<tr align="center">
     <td>
           <input type="button" value="/" onClick="SetExp('/')">
    </td>
     <td colspan="2">
           <input type="button" value="=" onClick="Cal()">
    </td>
    </tr>
</table>
</form>
</center>
</BODY>
</HTML>