C#正則判斷是否為數字

記得最開始 using System.Text.RegularExpressions;

Regex m_regex = new System.Text.RegularExpressions.Regex("^(-?[0-9]*[.]*[0-9]{0,3})$");
            bool b =  m_regex.IsMatch("111");
            if (b == false)
            {
                Console.WriteLine("請填寫數字");
                Console.ReadLine();
            }
            else
            {
                Console.WriteLine("正確的數字");
                Console.ReadLine();
            }