C# 字符串计算表达式

 C#  字符串计算表达式

string str="4+4+2.1";

要的效果： double sum=4+4+2.1；

方案一：

动态计算表达式：

 1  public class Expression  2  {  3 object instance;  4  MethodInfo method;  5 /// <summary>  6 /// 表达试运算  7 /// </summary>  8 /// <param name="expression">表达试</param>  9 public Expression(string expression) 10  { 11 if (expression.IndexOf("return") < 0) expression = "return " + expression + ";"; 12 string className = "Expression"; 13 string methodName = "Compute"; 14 CompilerParameters p = new CompilerParameters(); 15 p.GenerateInMemory = true; 16 CompilerResults cr = new CSharpCodeProvider().CompileAssemblyFromSource(p, string. 17 Format("using System;sealed class {0}{{public double {1}(double x){{{2}}}}}", 18  className, methodName, expression)); 19 if (cr.Errors.Count > 0) 20  { 21 string msg = "Expression(\"" + expression + "\"): \n"; 22 foreach (CompilerError err in cr.Errors) msg += err.ToString() + "\n"; 23 throw new Exception(msg); 24  } 25 instance = cr.CompiledAssembly.CreateInstance(className); 26 method = instance.GetType().GetMethod(methodName); 27  } 28 /// <summary> 29 /// 处理数据 30 /// </summary> 31 /// <param name="x"></param> 32 /// <returns>返回计算值</returns> 33 public double Compute(double x) 34  { 35 return (double)method.Invoke(instance, new object[] { x }); 36 }

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方案二：

欢迎你们提供！