拍拍尘土

//在引用中添加COM中的MicroSoft Script Control 1.0
//using MSScriptControl;

private void Form1_Load(object sender, System.EventArgs e)
{
MSScriptControl.ScriptControl sc=new MSScriptControl.ScriptControlClass();
sc.Language="JavaScript";
MessageBox.Show(sc.Eval("6+9-9*8").ToString());
}

请参考以下内容:

动态地生成用户输入的函数表达式(C#):
http://skyivben.cnblogs.com/archive/2005/10/31/265861.html

怎样将"20*10+5*20"这样的字符串表达式"计算"后返回结果300:
http://community.csdn.net/Expert/topic/4169/4169185.xml

http://www.codeproject.com/vb/net/math_expression_evaluator.asp