一个递归函数将让你通过ValidChars的所有组合运行：

A recursive function will let you run through all combinations of ValidChars:

    int maxlength = 12;
    string ValidChars;
    private void Dive(string prefix, int level)
    {
        level += 1;
        foreach (char c in ValidChars)
        {
            Console.WriteLine(prefix + c);
            if (level < maxlength)
            {
                Dive(prefix + c, level);
            }
        }
    }

分配一套有效的字符到ValidChars，要最大长度字符串的最大长度，然后调用潜水（，0）;和远离你去。

Assign the set of valid characters to ValidChars, the maximum length of string you want to maxlength, then call Dive("", 0); and away you go.