实验要求：

1、在wpf项目中编程实现一个简单计算器，具体要求如下：
1）实现+，-，*，/运算
2）可以连续进行计算。

效果如图：

*该程序中数字通过点击对应按钮输入，运算符包含四种常用运算，除此之外还有退格以及清空操作，输入以及运算结果在上方文本框内显示

1.首先，该程序中只涉及单次运算，所以我们可以在隐藏文件里声明两个全局变量来相应的保存operation前后两个数（字符串）。

string num1 = null; //运算符之前的数
string num2 = null; //运算符之后的数
string ope = null; //运算符

2.每次键入一个位数要判断放在num1里还是num2里。

private void button1_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button1.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button1.Content;
 textBox.Text = num2;
 }
}

3.键入运算符是对变量ope赋值(因为是单次计算，所以运算符没必要在文本框里显示)

private void buttonADD_Click(object sender, RoutedEventArgs e)
 {
 ope = "+";
 }

4.CE清空操作，将textbox中的内容以及所有变量清空

private void buttonCE_Click(object sender, RoutedEventArgs e)
 {
 //if (ope == null)
 //{
 // num1 = textBox.Text;
 //}
 //else
 //{
 // num2 = textBox.Text;
 //}
 this.textBox.Text = "";
 num1 = null;
 num2 = null;
 ope = null;
 }

5.退格操作

private void buttonBK_Click(object sender, RoutedEventArgs e)
 {
 string s = textBox.Text;
 int len = s.Length;
 if (textBox.Text != null && len >= 1)
 textBox.Text = s.Remove(len - 1);
 if (ope == null)
 {
 num1 = textBox.Text;
 }
 else
 {
 num2 = textBox.Text;
 }
}

6.计算结果（利用switch case ）

private void buttonEQ_Click(object sender, RoutedEventArgs e)
 {
 switch (ope)
 {
 case "+":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) + Convert.ToDouble(num2));
  break;
 case "-":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) - Convert.ToDouble(num2));
  break;
 case "*":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) * Convert.ToDouble(num2));
  break;
 case "/":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) / Convert.ToDouble(num2));
  break;
 }
 num1 = textBox.Text; 
 num2 = null;
 ope = null;
}

将结果值赋给num1来实现连续计算.

效果如如下：

完整代码如下：

*xaml

Window x:Class="小小计算器.MainWindow"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 Title="计算器" Height="382" Width="362">
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

.cs文件

namespace 小小计算器
{
 /// 

 /// MainWindow.xaml 的交互逻辑
 /// 
 public partial class MainWindow : Window
 {
 string num1 = null; //运算符之前的数
 string num2 = null; //运算符之后的数
 string ope = null; //运算符
 public MainWindow()
 {
 InitializeComponent();
 }

 private void button1_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button1.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button1.Content;
 textBox.Text = num2;
 }
 }

 private void button2_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button2.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button2.Content;
 textBox.Text = num2;
 }
 }

 private void button3_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button3.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button3.Content;
 textBox.Text = num2;
 }
 }

 private void button4_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button4.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button4.Content;
 textBox.Text = num2;
 }
 }

 private void button5_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button5.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button5.Content;
 textBox.Text = num2;
 }
 }

 private void button6_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button6.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button6.Content;
 textBox.Text = num2;
 }
 }

 private void button7_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button7.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button7.Content;
 textBox.Text = num2;
 }
 }

 private void button8_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button8.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button8.Content;
 textBox.Text = num2;
 }
 }

 private void button9_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button9.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button9.Content;
 textBox.Text = num2;
 }
 }
 private void button0_Click(object sender, RoutedEventArgs e)
 {
 if (ope == null)
 {
 num1 += button0.Content;
 textBox.Text = num1;
 }
 else
 {
 num2 += button0.Content;
 textBox.Text = num2;
 }
 }

 private void buttonADD_Click(object sender, RoutedEventArgs e)
 {
 ope = "+";
 }

 private void buttonSUB_Click(object sender, RoutedEventArgs e)
 {
 ope = "-";
 }

 private void buttonMUP_Click(object sender, RoutedEventArgs e)
 {
 ope = "*";
 }

 private void buttonDIV_Click(object sender, RoutedEventArgs e)
 {
 ope = "/";
 }

 private void buttonDOT_Click(object sender, RoutedEventArgs e)
 {

 if (ope == null &&!num1.Contains(".")) //如果num中已有小数点，则不允许再输入.
 {

 num1 += buttonDOT.Content;
 textBox.Text = num1;

 }
 if(ope!=null&&!num2.Contains("."))   
 {
 num2 += buttonDOT.Content;
 textBox.Text = num2;
 }
 }

 private void buttonCE_Click(object sender, RoutedEventArgs e)
 {
 //if (ope == null)
 //{
 // num1 = textBox.Text;
 //}
 //else
 //{
 // num2 = textBox.Text;
 //}
 this.textBox.Text = "";
 num1 = null;
 num2 = null;
 ope = null;
 }

 private void buttonBK_Click(object sender, RoutedEventArgs e)
 {
 string s = textBox.Text;
 int len = s.Length;
 if (textBox.Text != null && len >= 1)
 textBox.Text = s.Remove(len - 1);
 if (ope == null)
 {
 num1 = textBox.Text;
 }
 else
 {
 num2 = textBox.Text;
 }
 }

 private void buttonEQ_Click(object sender, RoutedEventArgs e)
 {
 switch (ope)
 {
 case "+":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) + Convert.ToDouble(num2));
  break;
 case "-":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) - Convert.ToDouble(num2));
  break;
 case "*":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) * Convert.ToDouble(num2));
  break;
 case "/":
  textBox.Text = Convert.ToString(Convert.ToDouble(num1) / Convert.ToDouble(num2));
  break;
 }
 num1 = textBox.Text;
 num2 = null;
 ope = null;
 }


 }
}