表达式计算器
一个表达式计算器,用C#写的,利用了VB编译器的强劲性能,可以计算任何合法的VB表达式,可以有一个自变量(x),也可以不要自变量。
计算表达式的代码用的是“银河”的代码(VB版):
http://www.cnblogs.com/skyivben/archive/2005/10/31/265861.html
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// Calc.cs - 表达式计算器
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// 编译方法: csc /t:winexe Calc.cs VBExpression.cs
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using System;
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using System.Windows.Forms;
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using Skyiv.Util;
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namespace Skyiv
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{
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class Calc : Form
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{
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TextBox tbxA1, tbxA2, tbxA3;
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Calc()
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{
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Text = "表达式计算器";
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StartPosition = FormStartPosition.CenterScreen;
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Width = 400;
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Height = 200;
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Label lblA1 = new Label();
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lblA1.Text = "表达式(&E)";
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lblA1.Parent = this;
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lblA1.Top = 23;
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lblA1.Left = 10;
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lblA1.AutoSize = true;
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tbxA1 = new TextBox();
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tbxA1.Parent = this;
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tbxA1.Top = 20;
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tbxA1.Left = 80;
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tbxA1.Width = 300;
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tbxA1.BorderStyle = BorderStyle.FixedSingle;
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Label lblA2 = new Label();
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lblA2.Text = "自变量(&X)";
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lblA2.Parent = this;
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lblA2.Top = 48;
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lblA2.Left = 10;
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lblA2.AutoSize = true;
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tbxA2 = new TextBox();
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tbxA2.Parent = this;
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tbxA2.Top = 45;
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tbxA2.Left = 80;
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tbxA2.Width = 300;
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tbxA2.BorderStyle = BorderStyle.FixedSingle;
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Button btnA3 = new Button();
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btnA3.Text = "计算(&C)";
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btnA3.Parent = this;
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btnA3.Top = 70;
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btnA3.Left = 10;
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btnA3.Width = 62;
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btnA3.Click += new EventHandler(Calc_Clicked);
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tbxA3 = new TextBox();
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tbxA3.Parent = this;
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tbxA3.Top = 70;
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tbxA3.Left = 80;
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tbxA3.Width = 300;
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tbxA3.BorderStyle = BorderStyle.FixedSingle;
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tbxA3.ReadOnly = true;
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TextBox tbxA4 = new TextBox();
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tbxA4.Text = @"
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表达式使用 Visual Baisc 语法,可带一个的自变量(x)
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可使用 pi、e 等常量,sin、cos、tan、log、sqrt 等函数
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例子:x * cos(x * pi / sqrt(25 * 6^4)) + log(E^10)";
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tbxA4.Parent = this;
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tbxA4.Top = 95;
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tbxA4.Left = 10;
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tbxA4.Width = 370;
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tbxA4.Height = 65;
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tbxA4.BorderStyle = BorderStyle.None;
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tbxA4.Multiline = true;
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tbxA4.ReadOnly = true;
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}
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void Calc_Clicked(object sender, EventArgs ea)
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{
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(sender as Control).Enabled = false;
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try
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{
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double x = 0;
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if (tbxA2.Text.Trim().Length != 0)
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{
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try
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{
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x = double.Parse(tbxA2.Text);
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}
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catch
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{
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try
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{
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x = (new Expression(tbxA2.Text)).Compute(0);
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}
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catch (Exception ex)
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{
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MessageBox.Show(ex.Message, "自变量出错");
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}
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}
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}
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tbxA3.Text = (new Expression(tbxA1.Text)).Compute(x).ToString();
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}
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catch (Exception ex)
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{
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MessageBox.Show(ex.Message, "表达式出错");
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}
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finally
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{
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(sender as Control).Enabled = true;
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}
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}
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[STAThread]
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static void Main(string [] args)
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{
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Application.Run(new Calc());
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}
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}
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}
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计算表达式的代码用的是“银河”的代码(VB版):
http://www.cnblogs.com/skyivben/archive/2005/10/31/265861.html
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// VBExpression.cs - 动态生成数学表达式并计算其值
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// 表达式使用 Visual Baisc 语法,可带一个的自变量(x)
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// 可使用 pi、e 等常量,sin、cos、tan、log、sqrt 等函数
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// 例子:e + sqrt(log(pi ^ e) * x) + sin(x * pi / 180)
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using System;
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using System.CodeDom.Compiler;
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using Microsoft.VisualBasic;
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using System.Reflection;
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using System.Text;
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using System.Globalization;
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namespace Skyiv.Util
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{
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sealed class Expression
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{
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object instance;
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MethodInfo method;
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public Expression(string expression)
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{
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if (expression.ToUpper(CultureInfo.InvariantCulture).IndexOf("RETURN") < 0) expression = "Return " + expression;
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string className = "Expression";
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string methodName = "Compute";
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CompilerParameters p = new CompilerParameters();
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p.GenerateInMemory = true;
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CompilerResults cr = new VBCodeProvider().CompileAssemblyFromSource
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(
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p,
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string.Format
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(
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@"Option Explicit Off
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Option Strict Off
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Imports System, System.Math, Microsoft.VisualBasic
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NotInheritable Class {0}
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Public Function {1}(x As Double) As Double
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{2}
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End Function
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End Class",
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className, methodName, expression
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)
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);
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if(cr.Errors.Count > 0)
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{
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string msg = "Expression(\"" + expression + "\"): \n";
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foreach (CompilerError err in cr.Errors) msg += err.ToString() + "\n";
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throw new Exception(msg);
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}
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instance = cr.CompiledAssembly.CreateInstance(className);
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method = instance.GetType().GetMethod(methodName);
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}
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public double Compute(double x)
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{
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return (double)method.Invoke(instance, new object [] { x });
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}
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}
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}
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