程序代码：

<script language=\"javascript\">

r=new Array(2);
function initialize(){
  currOper=\"start\";
  r[0]=\"0\";
  r[1]=\"0\";
  operand=\"\";
  ix=0;
}
function addDigit(n){
  if(currOper==\"Int\" || currOper==\"Float\")
    r[ix]=appendDigit(r[ix],n)
  else{
    r[ix]=\"\"+n;
    currOper=\"Int\";
  }
  showinForm(r[ix]);
}
function appendDigit(n1,n2){
  if(n1==\"0\")
    return \"\"+n2;
  var s=\"\";
  s+=n1;
  s+=n2;
  return s;
}
function showinForm(s){
  document.calculator.total.value=s;
}
function addDecimalPoint(){
  if(currOper!=\"Float\"){
    decimal=true;
    r[ix]+=\".\";
    if(currOper==\"Operator\" || currOper==\"getoperand\")
      r[ix]=\"0.\"
    currOper=\"Float\";
    showinForm(r[ix]);
  }
}
function clearDisplay(){
  initialize();
  showinForm(r[0]);
}
function changeSign(){
  if(r[ix].charAt(0)==\"-\")
    r[ix]=r[ix].substring(1,r[ix].length);
  else if(parseFloat(r[ix])!=0)
    r[ix]=\"-\"+r[ix];
  showinForm(r[ix]);
}
function setTo(n){
  r[ix]=\"\"+n;
  currOper=\"Operator\";
  decimal=false;
  showinForm(r[ix]);
}
function Count(){
  if(currOper==\"Int\" || currOper==\"Float\" || currOper==\"Operator\"){
    if(ix==1){
      r[0]=doCounting(operand,r[0],r[1]);
      ix=0;
    }
  }
  else if(currOper==\"getoperand2\"){
    r[0]=doCounting(operand,r[1],r[0]);
    ix=0;
  }
  currOper=\"Operator\";
  decimal==false;
  showinForm(r[ix]);
}
function doCounting(op,x,y){
  var result=\"\";
  switch(op){
    case \"+\":result=\"\"+(parseFloat(x)+parseFloat(y));break;
    case \"-\":result=\"\"+(parseFloat(x)-parseFloat(y));break;
    case \"*\":result=\"\"+(parseFloat(x)*parseFloat(y));break;
    case \"/\":if(parseFloat(y)==0){
               alert(\"分子为0，错误！\");
               result=0;
             }
             else result=\"\"+(parseFloat(x)/parseFloat(y));
             break;
  }
  return result;
}
function performOp(op){
  if(currOper==\"start\"){
    ++ix;
    operand=op;
  }
  else if(currOper==\"Int\" || currOper==\"Float\" || currOper==\"Operator\"){
    if(ix==0){
      ++ix;
      operand=op;
    }
    else{
      r[0]=doCounting(operand,r[0],r[1]);
      showinForm(r[0]);
      operand=op;
    }
  }
  currOper=\"getoperand2\";
  decimal=false;
}
function doFunction(){
  var selectionList=document.calculator.functions;
  var selIX=selectionList.selectedIndex;
  var sel=selectionList.options[selIX].value;
  switch(sel){
    case\"abs\":r[ix]=Math.abs(r[ix]);break;
    case\"acos\":r[ix]=Math.acos(r[ix]);break;
    case\"asin\":r[ix]=Math.asin(r[ix]);break;
    case\"atan\":r[ix]=Math.atan(r[ix]);break;
    case\"ceil\":r[ix]=Math.ceil(r[ix]);break;
    case\"cos\":r[ix]=Math.cos(r[ix]);break;
    case\"exp\":r[ix]=Math.exp(r[ix]);break;
    case\"floor\":r[ix]=Math.floor(r[ix]);break;
    case\"log\":r[ix]=Math.log(r[ix]);break;
    case\"sin\":r[ix]=Math.sin(r[ix]);break;
    case\"sqrt\":r[ix]=Math.sqrt(r[ix]);break;
    case\"tan\":r[ix]=Math.tan(r[ix]);break;
  }
  decimal=false;
  showinForm(r[ix]);
}