C#实现简单加减乘除计算器

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Text; 
using System.Windows.Forms; 
 
namespace WindowsApplication1 
{ 
 public partial class Main : Form 
 { 
  public Main() 
  { 
   InitializeComponent(); 
  } 
 
  private void Main_Load(object sender, EventArgs e) 
  { 
 
  } 
 
  private void txtInshu1_TextChanged(object sender, EventArgs e) 
  { 
 
  } 
 
  private void txtInshu1_KeyPress(object sender, KeyPressEventArgs e) 
  { 
   OnlyEnterNumber(sender, e); 
  } 
 
  //// <summary> 
  /// 只能输入数字（含负号小数点） 
  /// </summary> 
  /// <param name="sender"></param> 
  /// <param name="e"></param> 
  public static void OnlyEnterNumber(object sender, KeyPressEventArgs e) 
  { 
   if ((e.KeyChar < 48 || e.KeyChar > 57) && e.KeyChar != 8 && e.KeyChar != 13 && e.KeyChar != 45 && e.KeyChar != 46) 
   { 
    e.Handled = true; 
   } 
 
   // 输入为负号时，只能输入一次且只能输入一次 
   if (e.KeyChar == 45 && (((TextBox)sender).SelectionStart != 0 || ((TextBox)sender).Text.IndexOf("-") >= 0)) e.Handled = true; 
   if (e.KeyChar == 46 && ((TextBox)sender).Text.IndexOf(".") >= 0) e.Handled = true; 
  } 
 
 
  /* 
   * 参数：d表示要四舍五入的数；i表示要保留的小数点后位数。 
   * 正负数都四舍五入，适合数据统计的显示 
   */ 
  double Round(double d, int i) 
  { 
   if (d >= 0) 
   { 
    d += 5 * Math.Pow(10, -(i + 1)); 
   } 
   else 
   { 
    d += -5 * Math.Pow(10, -(i + 1)); 
   } 
   string str = d.ToString(); 
   string[] strs = str.Split('.'); 
   int idot = str.IndexOf('.'); 
   string prestr = strs[0]; 
   string poststr = strs[1]; 
   if (poststr.Length > i) 
   { 
    poststr = str.Substring(idot + 1, i); 
   } 
   string strd = prestr + "." + poststr; 
   d = Double.Parse(strd); 
   return d; 
  } 
 
  private void txtInshu2_TextChanged(object sender, EventArgs e) 
  { 
 
  } 
 
  private void txtInshu2_KeyPress_1(object sender, KeyPressEventArgs e) 
  { 
   OnlyEnterNumber(sender, e); 
  } 
 
  private void btnJisuan_Click(object sender, EventArgs e) 
  { 
   if (txtInshu1.Text == "") { 
    MessageBox.Show("因数1不能为空！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Warning); 
    return; 
   } 
   if (txtInshu2.Text == "") 
   { 
    MessageBox.Show("因数2不能为空！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Warning); 
    return; 
   } 
 
   double inshu1 = Convert.ToDouble(txtInshu1.Text); 
   double inshu2 = Convert.ToDouble(txtInshu2.Text); 
   double result = 0.0; 
 
   if (radioBtnJia.Checked) { 
    result = inshu1 + inshu2; 
   } 
 
   if (radioBtnJian.Checked) 
   { 
    result = inshu1 - inshu2; 
   } 
 
   if (radioBtnCheng.Checked) 
   { 
    result = inshu1 * inshu2; 
   } 
 
   if (radioBtnChu.Checked) 
   { 
    if (0 == inshu2) 
    { 
     MessageBox.Show("因数2做除数不能为0！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Warning); 
     return; 
    } 
    result = inshu1 / inshu2; 
    result = Round(result, 6); 
   } 
 
   txtResult.Text = Convert.ToString(result); 
  } 
 } 
}