1、生成一串以6开头后面是4,10~20之间个数的随机数字串
string str = "6".PadRight(new Random().Next(10, 20), '4');
2、随机生成6位字母加数字
/// <summary>6位随机的字母加数字
/// </summary>
/// <returns></returns>
private string SixRdmLetterAndNum()
{
//随机生成的6位(字母+数字)
string code = string.Empty;
string vchar = "asdfghjklqwertyuiopzxcvbnm0123456789ASDFGHJKLQWERTYUIOPZXCVBNM";
int codeLength = 6;
System.Random rand = new Random();
for (int i = 0; i < codeLength; i++)
{
int t = rand.Next(vchar.Length);
code += vchar[t];
}
return code;
}