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 }
方案二：
欢迎你们提供！