随机字符串生成器返回相同的字符串[重复]

您正在方法中创建Random实例，这导致它在快速连续调用时返回相同的值。我会做这样的事情：

private static Random random = new Random((int)DateTime.Now.Ticks);//thanks to McAdenprivate string RandomString(int size)    {        StringBuilder builder = new StringBuilder();        char ch;        for (int i = 0; i < size; i++)        { ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));       builder.Append(ch);        }        return builder.ToString();    }// get 1st random string string Rand1 = RandomString(4);// get 2nd random string string Rand2 = RandomString(4);// creat full rand stringstring docNum = Rand1 + "-" + Rand2;

（您的代码的修改版本）