/// <summary>
    /// 判斷是否為小數點數字且帶符號
    /// </summary>
    /// <param name="symbol">A:正負,P:正數</param>
    /// <param name="message">小數點位數</param>
    /// <param name="message">需檢查的數字參數</param>
    /// <returns>返回值</returns>
    public static bool CheckIsNumberic(string
 
 type, string message,int intLength)
    {
        System.Text.RegularExpressions.Regex rex;
        //(@"^\-?\d+(\.\d{1,2})?$")   正負
        //(@"^\d+(\.\d{1,2})?$")  正數

        switch (type)    //A  正負數  P 正數 positive N 負數 negative
        {
            case "A":
                rex = new System.Text.RegularExpressions.Regex(@"
 
^\-?\d+(\.\d{1," + intLength + "})?$");
                break;
            case "P":
                rex = new System.Text.RegularExpressions.Regex(@"^\d+(\.\d{1," + intLength + "})?$");
                break;
            default:
                rex = new System.Text.RegularExpressions.Regex(@"
 
^\-?\d+(\.\d{1," + intLength + "})?$");
                break;
        }
        if (rex.IsMatch(message))
        {
            return true;
        }
        else
            return false;
    }

//調用，比如不能超過2位小數
     CheckIsNumberic("P", txtUnitPrice.Text.Trim(), 2)

asp.net 經常用到需要判斷文本框是否輸入的數字是小數，有無正負，幾位小數，可以封裝一起判斷