C#编写的windows计算器的实例代码

using system;
using system.drawing;
using system.windows;
using system.windows.forms;
using system.collections;
using system.componentmodel;
using system.data;
namespace comput
{
    /// <summary>
    /// 这是一个计算器的简单实现。
    /// </summary>
    public class form1 : system.windows.forms.form
    {
        #region 控件声明
        private system.windows.forms.textbox txtshow;
        private system.windows.forms.groupbox groupbox1;
        private system.windows.forms.button btn_rev;
        private system.windows.forms.button btn_dot;
        private system.windows.forms.button btn_add;
        private system.windows.forms.button btn_equ;
        private system.windows.forms.button btn_sign;
        private system.windows.forms.button btn_sub;
        private system.windows.forms.button btn_mul;
        private system.windows.forms.button btn_0;
        private system.windows.forms.button btn_3;
        private system.windows.forms.button btn_2;
        private system.windows.forms.button btn_1;
        private system.windows.forms.button btn_6;
        private system.windows.forms.button btn_5;
        private system.windows.forms.button btn_4;
        private system.windows.forms.button btn_sqrt;
        private system.windows.forms.button btn_div;
        private system.windows.forms.button btn_7;
        private system.windows.forms.button btn_8;
        private system.windows.forms.button btn_9;
        private system.windows.forms.mainmenu mainmenu1;
        private system.windows.forms.menuitem menuitem1;
        private system.windows.forms.button btn_sqr;
        private system.windows.forms.menuitem menuitem2;
        private system.windows.forms.menuitem menuitem3;
        private system.windows.forms.menuitem menuitem4;
        private system.windows.forms.menuitem menuitem5;
        private system.windows.forms.menuitem menuitem6;
        private system.windows.forms.button c;
        private system.windows.forms.button ce;
        private system.windows.forms.menuitem menuitem8;
        private system.windows.forms.menuitem menuitem9;
        private system.windows.forms.menuitem menuitem10;
        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        private system.componentmodel.container components = null;
        public form1()
        {
            //
            // windows 窗体设计器支持所必需的
            //
            initializecomponent();
            //
            // todo: 在 initializecomponent 调用后添加任何构造函数代码
            //
        }
        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        protected override void dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null)
                {
                    components.dispose();
                }
            }
            base.dispose( disposing );
        }
       #endregion
        #region 各控件的属性的方法windows form designer generated code
        /// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void initializecomponent()
        {
            system.resources.resourcemanager resources = new system.resources.resourcemanager(typeof(form1));
            this.txtshow = new system.windows.forms.textbox();
            this.groupbox1 = new system.windows.forms.groupbox();
            this.c = new system.windows.forms.button();
            this.ce = new system.windows.forms.button();
            this.btn_rev = new system.windows.forms.button();
            this.btn_dot = new system.windows.forms.button();
            this.btn_add = new system.windows.forms.button();
            this.btn_equ = new system.windows.forms.button();
            this.btn_sign = new system.windows.forms.button();
            this.btn_sub = new system.windows.forms.button();
            this.btn_mul = new system.windows.forms.button();
            this.btn_0 = new system.windows.forms.button();
            this.btn_3 = new system.windows.forms.button();
            this.btn_2 = new system.windows.forms.button();
            this.btn_1 = new system.windows.forms.button();
            this.btn_6 = new system.windows.forms.button();
            this.btn_5 = new system.windows.forms.button();
            this.btn_4 = new system.windows.forms.button();
            this.btn_sqrt = new system.windows.forms.button();
            this.btn_div = new system.windows.forms.button();
            this.btn_7 = new system.windows.forms.button();
            this.btn_8 = new system.windows.forms.button();
            this.btn_9 = new system.windows.forms.button();
            this.btn_sqr = new system.windows.forms.button();
            this.mainmenu1 = new system.windows.forms.mainmenu();
            this.menuitem1 = new system.windows.forms.menuitem();
            this.menuitem2 = new system.windows.forms.menuitem();
            this.menuitem3 = new system.windows.forms.menuitem();
            this.menuitem4 = new system.windows.forms.menuitem();
            this.menuitem5 = new system.windows.forms.menuitem();
            this.menuitem6 = new system.windows.forms.menuitem();
            this.menuitem8 = new system.windows.forms.menuitem();
            this.menuitem9 = new system.windows.forms.menuitem();
            this.menuitem10 = new system.windows.forms.menuitem();
            this.groupbox1.suspendlayout();
            this.suspendlayout();
            //
            // txtshow
            //
            this.txtshow.backcolor = system.drawing.color.fromargb(((system.byte)(192)), ((system.byte)(192)), ((system.byte)(255)));
            this.txtshow.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.regular, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.txtshow.forecolor = system.drawing.color.purple;
            this.txtshow.location = new system.drawing.point(25, 8);
            this.txtshow.name = "txtshow";
            this.txtshow.size = new system.drawing.size(228, 23);
            this.txtshow.tabindex = 1;
            this.txtshow.text = "0.";
            this.txtshow.textalign = system.windows.forms.horizontalalignment.right;
            //
            // groupbox1
            //
            this.groupbox1.controls.add(this.c);
            this.groupbox1.controls.add(this.ce);
            this.groupbox1.controls.add(this.btn_rev);
            this.groupbox1.controls.add(this.btn_dot);
            this.groupbox1.controls.add(this.btn_add);
            this.groupbox1.controls.add(this.btn_equ);
            this.groupbox1.controls.add(this.btn_sign);
            this.groupbox1.controls.add(this.btn_sub);
            this.groupbox1.controls.add(this.btn_mul);
            this.groupbox1.controls.add(this.btn_0);
            this.groupbox1.controls.add(this.btn_3);
            this.groupbox1.controls.add(this.btn_2);
            this.groupbox1.controls.add(this.btn_1);
            this.groupbox1.controls.add(this.btn_6);
            this.groupbox1.controls.add(this.btn_5);
            this.groupbox1.controls.add(this.btn_4);
            this.groupbox1.controls.add(this.btn_sqrt);
            this.groupbox1.controls.add(this.btn_div);
            this.groupbox1.controls.add(this.btn_7);
            this.groupbox1.controls.add(this.btn_8);
            this.groupbox1.controls.add(this.btn_9);
            this.groupbox1.controls.add(this.btn_sqr);
            this.groupbox1.location = new system.drawing.point(24, 40);
            this.groupbox1.name = "groupbox1";
            this.groupbox1.size = new system.drawing.size(232, 184);
            this.groupbox1.tabindex = 21;
            this.groupbox1.tabstop = false;
            this.groupbox1.text = "计算机区";
            //
            // c
            //
            this.c.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.c.forecolor = system.drawing.color.red;
            this.c.location = new system.drawing.point(178, 48);
            this.c.name = "c";
            this.c.size = new system.drawing.size(36, 61);
            this.c.tabindex = 41;
            this.c.text = "c";
            this.c.click += new system.eventhandler(this.btn_oper);
            //
            // ce
            //
            this.ce.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.ce.forecolor = system.drawing.color.red;
            this.ce.location = new system.drawing.point(138, 16);
            this.ce.name = "ce";
            this.ce.size = new system.drawing.size(76, 29);
            this.ce.tabindex = 40;
            this.ce.text = "ce";
            this.ce.click += new system.eventhandler(this.btn_oper);
            //
            // btn_rev
            //
            this.btn_rev.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_rev.forecolor = system.drawing.color.blue;
            this.btn_rev.location = new system.drawing.point(178, 112);
            this.btn_rev.name = "btn_rev";
            this.btn_rev.size = new system.drawing.size(36, 29);
            this.btn_rev.tabindex = 39;
            this.btn_rev.text = "1/x";
            this.btn_rev.click += new system.eventhandler(this.btn_oper);
            //
            // btn_dot
            //
            this.btn_dot.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_dot.location = new system.drawing.point(98, 144);
            this.btn_dot.name = "btn_dot";
            this.btn_dot.size = new system.drawing.size(36, 29);
            this.btn_dot.tabindex = 38;
            this.btn_dot.tag = "0";
            this.btn_dot.text = ".";
            this.btn_dot.click += new system.eventhandler(this.btn_oper);
            //
            // btn_add
            //
            this.btn_add.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_add.forecolor = system.drawing.color.red;
            this.btn_add.location = new system.drawing.point(138, 144);
            this.btn_add.name = "btn_add";
            this.btn_add.size = new system.drawing.size(36, 29);
            this.btn_add.tabindex = 37;
            this.btn_add.text = "+";
            this.btn_add.click += new system.eventhandler(this.btn_oper);
            //
            // btn_equ
            //
            this.btn_equ.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_equ.forecolor = system.drawing.color.red;
            this.btn_equ.location = new system.drawing.point(178, 144);
            this.btn_equ.name = "btn_equ";
            this.btn_equ.size = new system.drawing.size(36, 29);
            this.btn_equ.tabindex = 36;
            this.btn_equ.text = "=";
            this.btn_equ.click += new system.eventhandler(this.btn_equ_click);
            //
            // btn_sign
            //
            this.btn_sign.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_sign.forecolor = system.drawing.color.blue;
            this.btn_sign.location = new system.drawing.point(58, 144);
            this.btn_sign.name = "btn_sign";
            this.btn_sign.size = new system.drawing.size(36, 29);
            this.btn_sign.tabindex = 35;
            this.btn_sign.text = "+/-";
            this.btn_sign.click += new system.eventhandler(this.btn_oper);
            //
            // btn_sub
            //
            this.btn_sub.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_sub.forecolor = system.drawing.color.red;
            this.btn_sub.location = new system.drawing.point(138, 112);
            this.btn_sub.name = "btn_sub";
            this.btn_sub.size = new system.drawing.size(36, 29);
            this.btn_sub.tabindex = 34;
            this.btn_sub.text = "-";
            this.btn_sub.click += new system.eventhandler(this.btn_oper);
            //
            // btn_mul
            //
            this.btn_mul.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_mul.forecolor = system.drawing.color.red;
            this.btn_mul.location = new system.drawing.point(138, 80);
            this.btn_mul.name = "btn_mul";
            this.btn_mul.size = new system.drawing.size(36, 29);
            this.btn_mul.tabindex = 33;
            this.btn_mul.text = "*";
            this.btn_mul.click += new system.eventhandler(this.btn_oper);
            //
            // btn_0
            //
            this.btn_0.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_0.forecolor = system.drawing.color.blue;
            this.btn_0.location = new system.drawing.point(18, 144);
            this.btn_0.name = "btn_0";
            this.btn_0.size = new system.drawing.size(36, 29);
            this.btn_0.tabindex = 32;
            this.btn_0.tag = "0";
            this.btn_0.text = "0";
            this.btn_0.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_3
            //
            this.btn_3.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_3.forecolor = system.drawing.color.blue;
            this.btn_3.location = new system.drawing.point(98, 112);
            this.btn_3.name = "btn_3";
            this.btn_3.size = new system.drawing.size(36, 29);
            this.btn_3.tabindex = 31;
            this.btn_3.tag = "3";
            this.btn_3.text = "3";
            this.btn_3.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_2
            //
            this.btn_2.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_2.forecolor = system.drawing.color.blue;
            this.btn_2.location = new system.drawing.point(58, 112);
            this.btn_2.name = "btn_2";
            this.btn_2.size = new system.drawing.size(36, 29);
            this.btn_2.tabindex = 30;
            this.btn_2.tag = "2";
            this.btn_2.text = "2";
            this.btn_2.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_1
            //
            this.btn_1.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_1.forecolor = system.drawing.color.blue;
            this.btn_1.location = new system.drawing.point(18, 112);
            this.btn_1.name = "btn_1";
            this.btn_1.size = new system.drawing.size(36, 29);
            this.btn_1.tabindex = 29;
            this.btn_1.tag = "1";
            this.btn_1.text = "1";
            this.btn_1.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_6
            //
            this.btn_6.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_6.forecolor = system.drawing.color.blue;
            this.btn_6.location = new system.drawing.point(98, 80);
            this.btn_6.name = "btn_6";
            this.btn_6.size = new system.drawing.size(36, 29);
            this.btn_6.tabindex = 28;
            this.btn_6.tag = "6";
            this.btn_6.text = "6";
            this.btn_6.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_5
            //
            this.btn_5.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_5.forecolor = system.drawing.color.blue;
            this.btn_5.location = new system.drawing.point(58, 80);
            this.btn_5.name = "btn_5";
            this.btn_5.size = new system.drawing.size(36, 29);
            this.btn_5.tabindex = 27;
            this.btn_5.tag = "5";
            this.btn_5.text = "5";
            this.btn_5.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_4
            //
            this.btn_4.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_4.forecolor = system.drawing.color.blue;
            this.btn_4.location = new system.drawing.point(18, 80);
            this.btn_4.name = "btn_4";
            this.btn_4.size = new system.drawing.size(36, 29);
            this.btn_4.tabindex = 26;
            this.btn_4.tag = "4";
            this.btn_4.text = "4";
            this.btn_4.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_sqrt
            //
            this.btn_sqrt.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_sqrt.forecolor = system.drawing.color.blue;
            this.btn_sqrt.location = new system.drawing.point(18, 16);
            this.btn_sqrt.name = "btn_sqrt";
            this.btn_sqrt.size = new system.drawing.size(76, 29);
            this.btn_sqrt.tabindex = 25;
            this.btn_sqrt.text = "sqrt";
            this.btn_sqrt.click += new system.eventhandler(this.btn_oper);
            //
            // btn_div
            //
            this.btn_div.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_div.forecolor = system.drawing.color.red;
            this.btn_div.location = new system.drawing.point(138, 48);
            this.btn_div.name = "btn_div";
            this.btn_div.size = new system.drawing.size(36, 29);
            this.btn_div.tabindex = 24;
            this.btn_div.text = "/";
            this.btn_div.click += new system.eventhandler(this.btn_oper);
            //
            // btn_7
            //
            this.btn_7.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_7.forecolor = system.drawing.color.blue;
            this.btn_7.location = new system.drawing.point(18, 48);
            this.btn_7.name = "btn_7";
            this.btn_7.size = new system.drawing.size(36, 29);
            this.btn_7.tabindex = 23;
            this.btn_7.tag = "7";
            this.btn_7.text = "7";
            this.btn_7.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_8
            //
            this.btn_8.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_8.forecolor = system.drawing.color.blue;
            this.btn_8.location = new system.drawing.point(58, 48);
            this.btn_8.name = "btn_8";
            this.btn_8.size = new system.drawing.size(36, 29);
            this.btn_8.tabindex = 22;
            this.btn_8.tag = "8";
            this.btn_8.text = "8";
            this.btn_8.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_9
            //
            this.btn_9.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_9.forecolor = system.drawing.color.blue;
            this.btn_9.location = new system.drawing.point(98, 48);
            this.btn_9.name = "btn_9";
            this.btn_9.size = new system.drawing.size(36, 29);
            this.btn_9.tabindex = 21;
            this.btn_9.tag = "9";
            this.btn_9.text = "9";
            this.btn_9.click += new system.eventhandler(this.btn_0_click);
            //
            // btn_sqr
            //
            this.btn_sqr.font = new system.drawing.font("宋体", 10.5f, system.drawing.fontstyle.bold, system.drawing.graphicsunit.point, ((system.byte)(134)));
            this.btn_sqr.forecolor = system.drawing.color.blue;
            this.btn_sqr.location = new system.drawing.point(98, 16);
            this.btn_sqr.name = "btn_sqr";
            this.btn_sqr.size = new system.drawing.size(36, 29);
            this.btn_sqr.tabindex = 19;
            this.btn_sqr.text = "sqr";
            this.btn_sqr.click += new system.eventhandler(this.btn_oper);
            //
            // mainmenu1
            //
            this.mainmenu1.menuitems.addrange(new system.windows.forms.menuitem[] {
                                                                                      this.menuitem8,
                                                                                      this.menuitem1,
                                                                                      this.menuitem4});
            //
            // menuitem1
            //
            this.menuitem1.index = 1;
            this.menuitem1.menuitems.addrange(new system.windows.forms.menuitem[] {
                                                                                      this.menuitem2,
                                                                                      this.menuitem3});
            this.menuitem1.text = "编辑(&e)";
            //
            // menuitem2
            //
            this.menuitem2.index = 0;
            this.menuitem2.text = "复制(&c)";
            this.menuitem2.click += new system.eventhandler(this.menuitem2_click);
            //
            // menuitem3
            //
            this.menuitem3.index = 1;
            this.menuitem3.text = "粘贴(&p)";
            this.menuitem3.click += new system.eventhandler(this.menuitem3_click);
            //
            // menuitem4
            //
            this.menuitem4.index = 2;
            this.menuitem4.menuitems.addrange(new system.windows.forms.menuitem[] {
                                                                                      this.menuitem5,
                                                                                      this.menuitem6});
            this.menuitem4.text = "帮助(&h)";
            //
            // menuitem5
            //
            this.menuitem5.index = 0;
            this.menuitem5.text = "帮助主题(&h)";
            this.menuitem5.click += new system.eventhandler(this.menuitem5_click);
            //
            // menuitem6
            //
            this.menuitem6.index = 1;
            this.menuitem6.text = "关于(&a)";
            this.menuitem6.click += new system.eventhandler(this.menuitem6_click);
            //
            // menuitem8
            //
            this.menuitem8.index = 0;
            this.menuitem8.menuitems.addrange(new system.windows.forms.menuitem[] {
                                                                                      this.menuitem9,
                                                                                      this.menuitem10});
            this.menuitem8.text = "文件(&f)";
            //
            // menuitem9
            //
            this.menuitem9.index = 0;
            this.menuitem9.text = "打开windows计算器(&o)";
            this.menuitem9.click += new system.eventhandler(this.menuitem9_click);
            //
            // menuitem10
            //
            this.menuitem10.index = 1;
            this.menuitem10.text = "退出(&q)";
            this.menuitem10.click += new system.eventhandler(this.menuitem10_click);
            //
            // form1
            //
            this.autoscalebasesize = new system.drawing.size(6, 14);
            this.clientsize = new system.drawing.size(278, 239);
            this.controls.add(this.groupbox1);
            this.controls.add(this.txtshow);
            this.formborderstyle = system.windows.forms.formborderstyle.fixed3d;
            this.icon = ((system.drawing.icon)(resources.getobject("$this.icon")));
            this.maximizebox = false;
            this.menu = this.mainmenu1;
            this.name = "form1";
            this.startposition = system.windows.forms.formstartposition.centerscreen;
            this.text = "计算器";
            this.groupbox1.resumelayout(false);
            this.resumelayout(false);
        }
        #endregion
        #region 各变量和常数的声明
        public const int null = 0;      // 定义操作码
        public const int add = 1;     //表示加
        public const int sub = 2;     //减
        public const int mul = 3;     //乘
        public const int div = 4;    //除
        public const int sqr = 5;    //求平方
        public const int sqrt = 6;   //求平方根
        public const int nodot  = 0;     // 定义是否点击了小数点,0 为没点
        public const int hasdot = 1;
        private double res = 0;         // 记录结果数
        private double tmp = 0;         // 当前输入的操作数
        private int opt = null;         // 记录操作码
        private int dot = nodot;    // 记录是否点击了小数点,0为没有点
        private int num = 0;        // 记录输入操作数的个数
        private int dotnum = 0;        // 记录小数点部分的个数       
        string stroper;            //获取操作符
        #endregion
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [stathread]
        static void main()
        {
            application.run(new form1());
        }
        /// <summary>
        #region 获取操作数事件
        //获取操作数事件
        private void btn_0_click(object sender, system.eventargs e)
        {
            system.windows.forms.button btntmp;
            double i;
            btntmp = sender as system.windows.forms.button;           
            if (btntmp != null)
            {
                if (dot == nodot)
                {
                    // 没有点击小数点
                    i = double.parse(btntmp.tag.tostring()); //取用户自定义的控件关联数,并转换成double型
                    tmp = tmp * 10 + i;
                    txtshow.text = tmp.tostring();   //将其放入文本显示屏啊
                }
                else   // 点击了小数点
                {                   
                    dotnum++;    //记录小数点部分的个数
                                                       // 生成小数部分的新的数值
                    i = double.parse(btntmp.tag.tostring()) / system.math.pow(10,dotnum);
                    tmp = tmp + i;  //将小数点后的值加到当前操做数
                    txtshow.text = tmp.tostring();
                }
            }
        }
        #endregion
        #region 等于事件和等于运算方法
        //等于事件
        private void btn_equ_click(object sender, system.eventargs e)
        {
            calc();
        }
        //等于运算方法
        private void calc()
        {
            // 生成结果
            if (num == 0 )    //是否有操作数,没有就返回0
            {
                res = 0;
                tmp = 0;
                txtshow.text = res.tostring();
                return;
            }
            switch (opt)  //找到对应的运算符进行计算
            {
                    // 加法
                case add:
                    res = res + tmp;                   
                    break;
                    // 减法
                case sub:
                    res = res - tmp;                   
                    break;
                    // 乘法
                case mul:
                    res = res * tmp;                   
                    break;
                    // 除法
                case div:
                    res = res / tmp;                   
                    break;
                    // 平方
                case sqr:
                    res = tmp * tmp;                   
                    break;
                    // 平方根
                case sqrt:
                    res = system.math.sqrt(tmp);                   
                    break;
                default:
                    return;
            }
            txtshow.text = res.tostring();   //结果输出到文本显示屏
            opt = null;  //运算符清空
            tmp=0;   
            dot = nodot;
                    //res = 0;
                    //num = 0;
        }
        #endregion
        #region 获取操作符运事件
        //获取操作符运事件
        private void btn_oper(object obj,eventargs ea)
        {
            button tmp1=(button)obj;
            stroper=tmp1.text;
            switch (stroper)
            {
                case "/":       //除法运算
                    if(opt!=null&&opt!=div)
                    {
                        calc();
                    }
                    opt = div;
                    if (num != 0)  //判断操作数的个数,如果两个就做二元运算
                    {
                        if (tmp != 0)
                            res = res / tmp;
                    }
                    else
                        res = tmp;
                    num++;                     
                    tmp = 0;
                    txtshow.text = res.tostring();
                    dot = nodot;
                    break;
                case "*":
                    // 乘法运算
                    if(opt!=null&&opt!=mul)
                    {
                        calc();
                    }
                    opt = mul;
                    if (num!= 0 )     //判断操作数的个数,如果两个就做二元运算   
                    {
                            if(tmp!=0)
                         res = res * tmp;
                    }
                    else
                        res = tmp;
                    num++;                                     
                    tmp = 0;
                    txtshow.text = res.tostring();
                    dot = nodot;
                    break;
                case "+":            //加法运算
                    if(opt!=null&&opt!=add)
                    {
                        calc();
                    }
                    opt = add;
                    if (num != 0)    //判断操作数的个数,如果两个就做二元运算
                        res = res + tmp;
                    else
                        res = tmp;
                    num++;                   
                    tmp = 0;
                    txtshow.text = res.tostring();
                    dot = nodot;
                    break;
                case "-":        //减法运算
                    if(opt!=null&&opt!=sub)
                    {
                        calc();
                    }
                    /*if(opt==add)
                    {
                        res=res+tmp;
                        tmp=0;
                    }*/
                    opt = sub;
                    if (num != 0)    //判断操作数的个数,如果两个就做二元运算
                        res = res - tmp;
                    else
                        res = tmp;
                    num++;                    
                    tmp = 0;
                    txtshow.text = res.tostring();
                    dot = nodot;
                    break;
                case "sqrt":     //平方根运算
                    if(opt!=null)
                    {
                        calc();
                    }
                    //opt=sqrt;
                    if (tmp > 0)  //要求操作数大于0
                    {
                        res = math.sqrt(tmp);
                        //res=tmp;
                    }
                    else if(res>0)
                        res= math.sqrt(res);
                        txtshow.text =res.tostring();
                    num++;   
                    tmp=0;
                    dot = nodot;
                    break;
                case "sqr":
                    // 平方运算
                    if(opt!=null)
                    {
                        calc();
                    }
                    //opt=sqr;
                    if (tmp != 0)
                    {
                        res = tmp * tmp;
                        //res=tmp;
                    }
                    else
                        res=res*res;
                    txtshow.text = res.tostring();
                    num++;   
                    tmp=0;
                    dot = nodot;
                    break;
                case "1/x":  //倒数运算
                    if(opt!=null)
                    {
                        calc();
                    }
                    if (tmp != 0)
                    {
                        res = 1 / tmp;
                        //res=tmp;
                    }
                    else                   
                    res=1/res;
                    txtshow.text = res.tostring();
                    tmp=0;
                    dot = nodot;
                    break;
                case ".":
                            // 点击了小数点
                    if(dot==hasdot)
                        return;
                    else
                    {
                        dot = hasdot;
                        dotnum = 0;
                    }                   
                    break;
                case "+/-":
                                // 点击了符号运算
                    if(tmp!=0)
                    {
                        tmp = -tmp;
                        txtshow.text = tmp.tostring();
                    }
                    else
                    {
                        res=-res;
                        //res=tmp;
                        txtshow.text = res.tostring();   
                    }
                    dot = nodot;
                    break;   
                case "ce":     //清除运算
                    res = 0;         // 记录结果数
                    tmp = 0;         // 当前输入的操作数
                    opt = null;         // 记录操作码
                    dot = nodot;    // 记录是否点击了小数点
                    num = 0;        // 记录输入操作数的个数
                    dotnum = 0;        // 记录小数点部分的个数
                    txtshow.text="";                   
                    break;
                case "c":         //清除运算
                    res = 0;         // 记录结果数
                    tmp = 0;         // 当前输入的操作数
                    opt = null;         // 记录操作码
                    dot = nodot;    // 记录是否点击了小数点
                    num = 0;        // 记录输入操作数的个数
                    dotnum = 0;        // 记录小数点部分的个数
                    txtshow.text="";
                    break;
            }
        }
        #endregion
        #region     主菜单事件
        //打开关于主题---调用windows xp中计算器的帮助
        private void menuitem5_click(object sender, system.eventargs e)
        {
            help.showhelp(this,"c:\\windows\\help\\calc.chm");       
        }
        //打开于我们
        private void menuitem6_click(object sender, system.eventargs e)
        {
            form2 fm=new form2();
            fm.show();
        }
        //复制
        private void menuitem2_click(object sender, system.eventargs e)
        {
            if(txtshow.selectionlength>0)
            {
                txtshow.copy();
            }
        }
        //
       //粘贴
        private void menuitem3_click(object sender, system.eventargs e)
        {
            txtshow.paste();
        }
          //调用windows xp中的计算器
        private void menuitem9_click(object sender, system.eventargs e)
        {
             help.showhelp(this,"c:\\windows\\system32\\calc.exe");
        }
        //退出
        private void menuitem10_click(object sender, system.eventargs e)
        {
            application.exit();
        }
        #endregion
    }
}

ps：这里再为大家推荐两款本站的在线计算器，都是采用js实现，相信对大家有一定借鉴作用：

在线标准计算器：

在线科学计算器：