代碼:
using System;
using System.CodeDom.Compiler;
using System.Reflection;
using System.Text;
using Microsoft.CSharp;
namespace Expression
{
/// <summary>
/// 計算運算式的類
/// </summary>
public class CalculateExpression
{
/// <summary>
/// 接受一個string類型的運算式並計算結果,返回一個object對象,靜態方法
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public static object Calculate(string expression)
{
string className = "Calc";
string methodName = "Run";
expression = expression.Replace("/", "*1.0/");
//設定編譯參數
CompilerParameters paras = new CompilerParameters();
paras.GenerateExecutable = false;
paras.GenerateInMemory = true;
//建立動態代碼
StringBuilder classSource = new StringBuilder();
classSource.Append("public class " + className + "\n");
classSource.Append("{\n");
classSource.Append(" public object " + methodName + "()\n");
classSource.Append(" {\n");
classSource.Append(" return " + expression + ";\n");
classSource.Append(" }\n");
classSource.Append("}");
//編譯代碼
CompilerResults result = new CSharpCodeProvider().CompileAssemblyFromSource(paras, classSource.ToString());
//擷取編譯後的程式集。
Assembly assembly = result.CompiledAssembly;
//動態調用方法。
object eval = assembly.CreateInstance(className);
MethodInfo method = eval.GetType().GetMethod(methodName);
object reobj = method.Invoke(eval, null);
GC.Collect();
return reobj;
}
}
}
調用:
object objCalc = Calculate("((1 + 2) * 3 + 6) / 5 ");
Console.WriteLine(objCalc.ToString()); //結果為3
Console.ReadLine();
注意點:
1、不支援sin、cos等數學函數
2、不支援[]、{}等括弧和除數字、+、-、*、/以外的字元,建議調用計算函數前進行輸入的驗證。
轉自:http://hi.baidu.com/programed/item/f43cc6d43c6f3848fa576875