方法一:
  
   
     
static bool isnumeric(string str)
  {
   if (str==null || str.length==0)
    return false;
   foreach(char c in str)
   {
    if (!char.isnumber(c))
    {
     return false;
    }
   }
   return true;
  }

    方法二:

private bool isnumeric(string s)

private bool isnumeric(string s)

         {

              char ch0 = '0';

              char ch9 = '9';

              for(int i=0; i < s.length; i++)

              {

                  if ((s[i] < ch0 || s[i] > ch9))

                   {

                         this.lblwarning.text="此處應(yīng)輸入整數(shù)且非負(fù)！";

                         return false;

                   }

              }

              return true;

         }

    方法三:

static bool isnumeric (string str)
{  
   system.text.regularexpressions.regex reg1 
       = new system.text.regularexpressions.regex(@"^[-]?/d+[.]?/d*$"); 
   return reg1.ismatch(str);
}

    方法四：（可擴(kuò)展）

public static bool isconvert(string expression,type datatype)

{

  switch(datatype.name)

  {

       case "double":

              try

              {

                     double.parse(expression);

                     return true;

              }

              catch

              {

                     return false;

              }

       case "datetime":

              try

              {

                     datetime.parse(expression);

                     return true;

              }

              catch

              {

                     return false;

              }

       default:

              return true;

  }

}

    c#驗證輸入的是否數(shù)字的方法

其實用正則表達(dá)式也可以
static bool isnumeric(string str)
  {
   if (str==null || str.length==0)
    return false;
   foreach(char c in str)
   {
    if (!char.isnumber(c))
    {
     return false;
    }
   }
   return true;
  }

正則表達(dá)的寫法是：