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【CSharp】 C#.NET 动态计算表达式值

作者:Dezai.CN / 发布于2012/8/13/ 529

C#.NET 动态计算表达式值

<div>using System;
using System.CodeDom.Compiler;
using Microsoft.CSharp;
using System.Reflection;</div>
<div>namespace Pub.Class {
 /// <summary>
 /// 处理表达试运算---动态生成数学表达式并计算其值
 /// 表达式使用 C# 语法，可带一个的自变量(x)。
 /// 表达式的自变量和值均为(double)类型。
 /// </summary>
 /// <example>
 /// 
 /// Expression expression = new Expression("Math.Sin(x)"); 
 /// Console.WriteLine(expression.Compute(Math.PI / 2)); 
 /// expression = new Expression("double u = Math.PI - x;" + 
 /// "double pi2 = Math.PI * Math.PI;" + 
 /// "return 3 * x * x + Math.Log(u * u) / pi2 / pi2 + 1;"); 
 /// Console.WriteLine(expression.Compute(0)); 
 /// 
 /// Expression expression = new Expression("return 10*(5+5)/10;");
 /// Response.Write(expression.Compute(0));
 /// Response.End();
 /// 
 /// </example>
 public class Expression {
 object instance;
 MethodInfo method;
 /// <summary>
 /// 表达试运算
 /// </summary>
 /// <param name="expression">表达试</param>
 public Expression(string expression) {
 if (expression.IndexOf("return") < 0) expression = "return " + expression + ";";
 string className = "Expression";
 string methodName = "Compute";
 CompilerParameters p = new CompilerParameters();
 p.GenerateInMemory = true;
 CompilerResults cr = new CSharpCodeProvider().CompileAssemblyFromSource(p, string.
 Format("using System;sealed class {0}{{public double {1}(double x){{{2}}}}}",
 className, methodName, expression));
 if (cr.Errors.Count > 0) {
 string msg = "Expression(\"" + expression + "\"): \n";
 foreach (CompilerError err in cr.Errors) msg += err.ToString() + "\n";
 throw new Exception(msg);
 }
 instance = cr.CompiledAssembly.CreateInstance(className);
 method = instance.GetType().GetMethod(methodName);
 }
 /// <summary>
 /// 处理数据
 /// </summary>
 /// <param name="x"></param>
 /// <returns>返回计算值</returns>
 public double Compute(double x) {
 return (double)method.Invoke(instance, new object[] { x });
 }
 }
}

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　动态计算表达式值　

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