C#隨機產生不重複字串

      今天整理以前一個項目源碼，發現兩個隨機產生不重複字串的方法，覺得用起來挺方便的，在此貼出來，方便以後查閱。

        方法一：隨機產生不重複數字字串

       private int rep=0;

       /// <summary>
       /// 產生隨機數字字串
       /// </summary>
       /// <param name="codeCount">待產生的位元</param>
       /// <returns>產生的數字字串</returns>
       private string GenerateCheckCodeNum(int codeCount)
       {
           string str = string.Empty;
           long num2 = DateTime.Now.Ticks + this.rep;
           this.rep++;
           Random random = new Random(((int)(((ulong)num2) & 0xffffffffL)) | ((int)(num2 >> this.rep)));
           for (int i = 0; i < codeCount; i++)
           {
               int num = random.Next();
               str = str + ((char)(0x30 + ((ushort)(num % 10)))).ToString();
           }
           return str;
       }

        方法二：隨機產生字串（數字和字母混和）

       /// <summary>
       /// 產生隨機字母字串(數字字母混和)
       /// </summary>
       /// <param name="codeCount">待產生的位元</param>
       /// <returns>產生的字母字串</returns>
       private string GenerateCheckCode(int codeCount)
       {
           string str = string.Empty;
           long num2 = DateTime.Now.Ticks + this.rep;
           this.rep++;
           Random random = new Random(((int)(((ulong)num2) & 0xffffffffL)) | ((int)(num2 >> this.rep)));
           for (int i = 0; i < codeCount; i++)
           {
               char ch;
               int num = random.Next();
               if ((num % 2) == 0)
               {
                   ch = (char)(0x30 + ((ushort)(num % 10)));
               }
               else
               {
                   ch = (char)(0x41 + ((ushort)(num % 0x1a)));
               }
               str = str + ch.ToString();
           }
           return str;
       }