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<html>
<head>
<title>calculate</title>
<style type="text/css">
.bg{
width:30%;
height:450px;
background:rgb(168,168,168);
margin-left:35%;
margin-right:35%;/*设置计算器居中*/
}
.uup{
width:100%;
height:9%;
text-align:"center";
}
.up{
width:88%;
height:12%;
border:solid 1px black;
margin:3% 6% 1.5% 6%;/*上右下左*/
}
.down{
width:88%;
height:70%;
border:solid 1px black;
margin:1.5% 6% 3% 6%;
}
.logo{
width:36%;
height:100%;
margin-top:0px;
margin-left:0px;/*边距*/
padding-left:30px;/*div与内容距离*/
background-color:white;
font-size:28px;
}
.show{
width:100%;
height:100%;
}
.numtable{
width:90%;
height:90%;
margin:5%;
}
.numtable tr td{
width:25%;
height:20%;/*设置每个表格大小一样*/
}
.numtable input{
width:80%;
height:80%;
margin:10%;/*使按钮在表格中居中显示*/
}
</style>
<script type="text/javascript">
window.onload=initZero;
var str = new Array();//保留输入字符数组
var numStr = new Array();//数字栈
var charStr = new Array();//运算符栈
var flag = new Array();//负数标志位，true表示负数，与运算符栈相等
var buttonId = new Array("reset","plus","minus","del","num7","num8","num9","multiply","num4","num5","num6","divide","num1","num2","num3","point","leftbracket","num0","rightbracket","equal");
//按钮ID名
function $(id){
return document.getElementById(id);
}
function initZero(){
$("inputframe").value=0;//结果显示框清零
initCE();//保存数据的栈和数组“清空”
addListener();//为每个按钮添加click事件监听器
}
function initCE(){
while(str.length!=0){
str.pop();//删除数组最后一个元素
}
while(numStr.length!=0){
numStr.shift();//删除数组第一个元素
}
while(charStr.length!=0){
charStr.shift();//删除数组第一个元素
}
while(flag.length!=0){
flag.shift();
}
charStr[0] = "0";//运算符栈先插入一个优先级最低的“0”元素
flag[0] = false;
}
function addListener(){
for (var i=0; i<buttonId.length; i++){
$(buttonId[i]).addEventListener("click",function(){//为每个按钮添加click事件监听器
if(this.id == "equal"){//如果按下”=“按钮
var result = getResult();
/*if (isNaN(result)){
alert("输入有错误！");
}else{//numStr[0]位结果，按下equal时不清空*/
if(str.length==0){
$("inputframe").value = 0;
}else{
$("inputframe").value = showStr() + "=" + result;
initCE();
}
}else if(this.id == "reset"){
initCE();//如果按下“CE”，进行复位,数字栈，运算符栈清空并插入“0”元素
$("inputframe").value = "0";//显示结果框清空
}else if(this.id == "del"){
str.pop();//按下“del”,撤回
$("inputframe").value = showStr();
}else{//如果按下其他运算符和数字按钮，插入str数组中
str.push(this.value);
$("inputframe").value = showStr();//显示结果框中数字随着按钮按下不断增加
}
});
}
}
function mul(num1,num2){//JavaScript存在小数计算精度丢失的问题,通过升级降级移动小数点解决
var pointNum1 = 0;
var pointNum2 = 0;
var numStr1 = num1.toString();
var numStr2 = num2.toString();
if(numStr1.indexOf(".",0)!=-1){
pointNum1 = numStr1.length-numStr1.indexOf(".",0)-1;//小数点个数
num1 = Number(numStr1.replace(".",""));//移动小数点将实数升级
}
if(numStr2.indexOf(".",0)!=-1){
pointNum2 = numStr2.length-numStr2.indexOf(".",0)-1;
num2 = Number(numStr2.replace(".",""));
}
var pointNum = pointNum1+pointNum2;//运算结果小数点个数
var resStr = (num1*num2).toString();
if(pointNum!=0){
if(resStr.length>pointNum){//升级后运算结果位数比小数点位数多
var num = resStr.length-pointNum;
var sstr = resStr.split("");
resStr="";
for(var i=0;i<num;i++){
resStr = resStr.concat(sstr[i]);
}
resStr = resStr.concat(".");
for(var i=num;i<sstr.length;i++){
resStr = resStr.concat(sstr[i]);
}
}else{
var zero = "0";
var point = ".";
var num = pointNum-resStr.length+2;
for(var i=0;i<num;i++){
if(i==num-2){
resStr = point.concat(resStr);
}else{
resStr = zero.concat(resStr);
}
}
}
}
return Number(resStr);
}
function div(num1,num2){
var pointNum1 = 0;
var pointNum2 = 0;
var numStr1 = num1.toString();
var numStr2 = num2.toString();
if(numStr1.indexOf(".",0)!=-1){
pointNum1 = numStr1.length-numStr1.indexOf(".",0)-1;
num1 = Number(numStr1.replace(".",""));
}
if(numStr2.indexOf(".",0)!=-1){
pointNum2 = numStr2.length-numStr2.indexOf(".",0)-1;
num2 = Number(numStr2.replace(".",""));
}
var resStr = num2/num1;
var pointNum = pointNum1>pointNum2?pointNum1-pointNum2:pointNum2-pointNum1;
var pointSum = 1;
if(pointNum!=0){
for(var i = 0; i< pointNum; i++){
pointSum = pointSum*10;
}
resStr = resStr/pointSum;
}
return resStr;
}
function charRes(num1, num2, ch){//根据表达式返回运算结果
var res = 0;
switch(ch){
case "+":res = num2+num1;break;
case "-":res = num2-num1;break;
//case "*":res = num2*num1;break;
case "*":res = mul(num1,num2);break;
//case "/":res = num2/num1;break;
case "/":res = div(num1,num2);break;
}
//JavaScript存在小数计算精度丢失的问题
return res;
}
function charNum(str){//为每个运算符指定数组下标
var num = 0;
switch(str){
case "+":num = 0;break;
case "-":num = 1;break;
case "*":num = 2;break;
case "/":num = 3;break;
case "(":num = 4;break;
case ")":num = 5;break;
case "0":num = 5;break;
}
return num;
}
function judgePriority(str1,str2){
//通过operator二维数组的值，判断运算符优先级，大于零表示str1优先级大，
//等于零表示遇到括号，小于零表示str2优先级大
var operator = new Array(6);
operator[0] = new Array(-1,-1,1,1,1,0);
operator[1] = new Array(-1,-1,1,1,1,0);
operator[2] = new Array(-1,-1,-1,-1,1,0);
operator[3] = new Array(-1,-1,-1,-1,1,0);
operator[4] = new Array(1,1,1,1,1,0);
operator[5] = new Array(1,1,1,1,1,0);
//下面为二位数组的格式
/* + - x / ( )
+
-
X
/
(
0
*/
var i = charNum(str1);
var j = charNum(str2);
return operator[i][j];
}
function getResult(){//返回总运算结果
var j = 0;
var finalNum = "";//将数字分离出来
var fflag;
for(var i=0; i<str.length; i++){
finalNum = "";
fflag = false;
if(!isNaN(str[i])){//如果是数字,可能是多位
j = i+1;
while(j<str.length){//找到可能是多位数字的最后一位,j-1位最后一位
if(!isNaN(str[j])){//是数字
j++;
}else if(str[j]=="."){
j++;
}else{
break;
}
}
for (m=i; m<j; m++){//将纯数字字符串分离出来
finalNum += str[m];
}
numStr.unshift(Number(finalNum));//操作数入numStr栈
i = j-1;
}
else{
//负数只有下面两种情况
if(str[i]=="-"){
if(i==0){//如果为-6+4*3
fflag=true;
}else {
if(str[i-1]=="("){//如果为5+(-6-2)
fflag=true;//flag=true代表为负数
}else{
fflag=false;
}
}
}
//alert("flag:"+flag);
if(judgePriority(charStr[0],str[i]) > 0){//前面优先级大,则入charStr栈
charStr.unshift(str[i]);
flag.unshift(fflag);
}else{
var ch = charStr.shift();
if(judgePriority(charStr[0],str[i]) == 0){//当碰到右括号时
while(ch!="("){
var num1 = numStr.shift();
if(ch=="-" && flag[0]==true){
numStr.unshift(0);
}
flag.shift();
var num2 = numStr.shift();
//alert("two:" + charRes(num1,num2,ch));
numStr.unshift(charRes(num1,num2,ch));//并将新的操作数入numStr栈
ch = charStr.shift();//直到弹出左括号
版权声明：本文来源CSDN，感谢博主原创文章，遵循 CC 4.0 by-sa 版权协议，转载请附上原文出处链接和本声明。
原文链接：https://blog.csdn.net/qq_36336003/article/details/80489706
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-
发表于 2020-03-08 16:19:38
- 阅读 ( 837 )
- 分类：前端
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