前台：

后台：

 String Fh = "";//用于存储符号运算符
        double a, b, c;//a为第一个接收的值，b为第二个值，c为计算结果
        long s = 1;//初始小数的位数
        // 构造函数
        public MainPage()
        {
            InitializeComponent();
        }

        public  void anniu(double i)//按钮的方法            
        {
            if (Fh.Equals(""))//是否当前有运算符      
            {              
                if (s == 1)//判断是否有小数点    
                {             
                    a = a * 10 + i;//计算无小数的值   
                }
                else
                {     
                    a = a + i / s;//计算有小数的值    
                    s = s * 10;//计算下一个小数的位置      
                }
                txtEntrty.Text = a.ToString();//显示计算的结果   
            }      
            else //当前有运算符的方法    
            {
                if (!(c == 0))
                {
                    b = 0;
                    c = 0;
                }//当有计算结果就清除B的值      
                if (s == 1)//判断是否有小数点    
                {
                    b = b * 10 + i;//计算无小数的值    
                }
                else  
                {
                    if (i == 0)//判断在小数位后添加0      
                    {
                        s = s * 10;//计算下一个小数的位置      
                    }
                    else 
                    {
                        b = b + i / s;//计算有小数的值  
                        s = s * 10;//计算下一个小数的位置    
                    }
                }
                txtEntrty.Text = b.ToString();//显示计算的结果       
            } 
        }

        public void js()
        {//数学计算的方法
            if (Fh=="/")//判断是否除数等于0     
            {   
                if (b == 0) //是则不计算     
                {
                    txtEntrty.Text = "被除数不能为0";//显示被除数不能为0    
                    return;//返回      
                }
                else
                {    
                    c = a / b;    
                }
            }        
            else//如果不是出发计算则执行其他计算   
            {
                if (Fh.Equals("+"))
                {
                    c = a + b;
                }
                if (Fh.Equals("-"))
                {
                    c = a - b;
                }
                if (Fh.Equals("*"))
                {
                    c = a * b;
                }
                if (Fh.Equals("%"))
                {
                    c = a % b;
                }     
            }
            txtEntrty.Text = c.ToString(); //显示计算结果     
            a = c;//将结果给第一个变量作为       
        }

        public void fh(string str) //接收运算符的方法   
        {
            if (Fh.Equals(""))//当前是否已经有运算符    
            {
                Fh = str;
                s = 1;//没有则接收运算符,小数点失效        
            }
            else
            {
                js();
                s = 1;
                Fh = str;//有则计算当前的值,小数点失效
            }  
        }    

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            anniu(7);//调用按钮方法    
        }

        private void button7_Click(object sender, RoutedEventArgs e)
        {
            anniu(1);//调用按钮方法    
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            anniu(8);//调用按钮方法    
        }

        private void button3_Click(object sender, RoutedEventArgs e)
        {
            anniu(9);//调用按钮方法    
        }

        private void button4_Click(object sender, RoutedEventArgs e)
        {
            anniu(4);//调用按钮方法    
        }

        private void button5_Click(object sender, RoutedEventArgs e)
        {
            anniu(5);//调用按钮方法    
        }

        private void button6_Click(object sender, RoutedEventArgs e)
        {
            anniu(6);//调用按钮方法    
        }

        private void button8_Click(object sender, RoutedEventArgs e)
        {
            anniu(2);//调用按钮方法    
        }

        private void button9_Click(object sender, RoutedEventArgs e)
        {
            anniu(3);//调用按钮方法    
        }

        private void button10_Click(object sender, RoutedEventArgs e)
        {
            if (!txtEntrty.Text.Equals("0"))
            {
                anniu(0);
            }
        }

        private void button16_Click(object sender, RoutedEventArgs e)//正负号
        {
            if (Fh.Equals(""))
            {
                a = -a;
                txtEntrty.Text = a.ToString();
            }
            else
            {
                b = -b;
                txtEntrty.Text = b.ToString();
            }//初始当前值的正负号     
        }

        private void button19_Click(object sender, RoutedEventArgs e)//清空按钮
        {
            txtEntrty.Text = "0";//清空TEXTBOX的显示值      
            a = 0;
            b = 0;
            c = 0;
            s = 1;
            Fh = "";//初始化所有值    
        }

        private void button18_Click(object sender, RoutedEventArgs e)//等于号
        {
            js();//调用计算方法
        }

        private void button11_Click(object sender, RoutedEventArgs e)//小数点
        {
            if (s == 1)
            {
                s = 10;
            }//如果之前有过使用小数点则跳过当前小数点按钮的方法,否则初始小数点的 
        }

        private void button15_Click(object sender, RoutedEventArgs e)
        {
            fh("+");//调用运算符的方法
        }

        private void button14_Click(object sender, RoutedEventArgs e)
        {
            fh("-");//调用运算符的方法
        }

        private void button13_Click(object sender, RoutedEventArgs e)
        {
            fh("*");//调用运算符的方法
        }

        private void button12_Click(object sender, RoutedEventArgs e)
        {
            fh("/");//调用运算符的方法
        }

        private void button17_Click(object sender, RoutedEventArgs e)
        {
            fh("%");//调用运算符的方法
        }