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); 
    } 
  } 
}