Unique identifiers: Base62

gistfile1.cs

public static string Base62Random()
{
	int random = _random.Next();
	return Base62ToString(random);
}

private static string Base62ToString(long value)
{
	// Divides the number by 64, so how many 64s are in
	// 'value'. This number is stored in Y.
	// e.g #1
	// 1) 1000 / 62 = 16, plus 8 remainder (stored in x).
	// 2) 16 / 62 = 0, remainder 16
	// 3) 16, 8 or G8:
	// 4) 65 is A, add 6 to this = 71 or G.
	//
	// e.g #2:
	// 1) 10000 / 62 = 161, remainder 18
	// 2) 161 / 62 = 2, remainder 37
	// 3) 2 / 62 = 0, remainder 2
	// 4) 2, 37, 18, or 2,b,I:
	// 5) 65 is A, add 27 to this (minus 10 from 37 as these are digits) = 92.
	//    Add 6 to 92, as 91-96 are symbols. 98 is b.
	// 6)
	long x = 0;
	long y = Math.DivRem(value, 62, out x);
	if (y > 0)
		return Base62ToString(y) + ValToChar(x).ToString();
	else
		return ValToChar(x).ToString();
}

private static char ValToChar(long value)
{
	if (value > 9)
	{
		int ascii = (65 + ((int)value - 10));
		if (ascii > 90)
			ascii += 6;
		return (char)ascii;
	}
	else
		return value.ToString()[0];
}