如何在C#中运行数学表达式字符串

如何在C#中运行数学表达式字符串

方法1：利用DataTable中的Compute方法

1 string expression = "1+2*3"; 2 DataTable eval = new DataTable();object result = eval.Compute(expression, “”);

方法2：利用xPath表达式

1 publicstaticdoubleEvaluate(string expression) 2 { 3 return(double)newSystem.Xml.XPath.XPathDocument 4 (newStringReader("")).CreateNavigator().Evaluate 5 (string.Format("number({0})",new 6 System.Text.RegularExpressions.Regex(@"([\+\-\*])") 7 .Replace(expression," ${1} ") 8 .Replace("/"," div ") 9 .Replace("%"," mod "))); 10 }

//方法3：利用python里面的计算表达式方法   

View Code

方法4：在网上找了一个计算表达式的类库

/// <summary>

    /// 动态求值
    /// </summary>
    public class Evaluator
    {
        /// <summary>
        /// 计算结果,如果表达式出错则抛出异常
        /// </summary>
        /// <param name="statement">表达式,如"1+2+3+4"</param>
        /// <returns>结果</returns>
        public static object Eval(string statement)
        {
            return _evaluatorType.InvokeMember(
                        "Eval",
                        BindingFlags.InvokeMethod,
                        null,
                        _evaluator,
                        new object[] { statement }
                     );
        }
        /// <summary>
        /// 
        /// </summary>
        static Evaluator()
        {
            //构造JScript的编译驱动代码
            CodeDomProvider provider = CodeDomProvider.CreateProvider("JScript");


            CompilerParameters parameters;
            parameters = new CompilerParameters();
            parameters.GenerateInMemory = true;


            CompilerResults results;
            results = provider.CompileAssemblyFromSource(parameters, _jscriptSource);


            Assembly assembly = results.CompiledAssembly;
            _evaluatorType = assembly.GetType("Evaluator");


            _evaluator = Activator.CreateInstance(_evaluatorType);
        }


        private static object _evaluator = null;
        private static Type _evaluatorType = null;
        /// <summary>
        /// JScript代码
        /// </summary>
        private static readonly string _jscriptSource =


            @"class Evaluator
              {
                  public function Eval(expr : String) : String 
                  { 
                     return eval(expr); 
                  }
              }";
    }