/// <summary>
/// Generate a unique ID.
/// </summary>
/// <remarks>
/// With an empty prefix, the returned string will be 14 characters long. If more_entropy is TRUE, it will be 23 characters.
/// </remarks>
/// <param name="prefix">Use the specified prefix.</param>
/// <param name="more_entropy">Use LCG to generate a random postfix.</param>
/// <returns>A pseudo-random string composed from the given prefix, current time and a random postfix.</returns>
public static string uniqid(string prefix = "", bool more_entropy = false)
{
// Note that Ticks specify time in 100nanoseconds but it is raised each 100144
// ticks which is around 10 times a second (the same for Milliseconds).
const int tickslength = 14;
// 14 digits, hexadecimal, lowercased
var ticks = ((ulong)(System.DateTime.UtcNow.Ticks + MTGenerator.Next()))
.ToString("x" /*x14*/, CultureInfo.InvariantCulture);
if (ticks.Length > tickslength)
{
ticks = ticks.Remove(tickslength);
}
else if (ticks.Length < tickslength)
{
ticks = ticks.PadLeft(tickslength, '0');
}
if (more_entropy)
{
// 8 digits from the lcg:
var rnd = ((ulong)(lcg_value() * 100_000_000)).ToString("d8", CultureInfo.InvariantCulture);
return(prefix + ticks + "." + rnd);
}
else
{
return(prefix + ticks);
}
}
/// <summary>
/// Generate a unique ID.
/// </summary>
/// <remarks>
/// With an empty prefix, the returned string will be 13 characters long. If more_entropy is TRUE, it will be 23 characters.
/// </remarks>
/// <param name="prefix">Use the specified prefix.</param>
/// <param name="more_entropy">Use LCG to generate a random postfix.</param>
/// <returns>A pseudo-random string composed from the given prefix, current time and a random postfix.</returns>
public static string uniqid(string prefix, bool more_entropy)
{
// Note that Ticks specify time in 100nanoseconds but it is raised each 100144
// ticks which is around 10 times a second (the same for Milliseconds).
string ticks = string.Format("{0:X}", System.DateTime.UtcNow.Ticks + MTGenerator.Next());
ticks = ticks.Substring(ticks.Length - 13);
if (prefix == null)
{
prefix = "";
}
if (more_entropy)
{
string rnd = lcg_value().ToString();
rnd = rnd.Substring(2, 8);
return(string.Format("{0}{1}.{2}", prefix, ticks, rnd));
}
else
{
return(string.Format("{0}{1}", prefix, ticks));
}
}
/// <summary>
/// Seed the better random number generator.
/// No return value.
/// </summary>
/// <param name="seed">Optional seed value.</param>
public static void mt_srand(int seed)
{
MTGenerator.Seed(unchecked ((uint)seed));
}
public static int mt_rand(int min, int max)
{
return((min < max) ? MTGenerator.Next(min, max) : MTGenerator.Next(max, min));
}
public static int mt_rand()
{
return(MTGenerator.Next());
}
/// <summary> /// Generates a pseudo-random number using linear congruential generator in the range of (0,1). /// </summary> /// <remarks> /// This method uses the Framwork <see cref="rand()"/> generator /// which may or may not be the same generator as the PHP one (L(CG(2^31 - 85),CG(2^31 - 249))). /// </remarks> /// <returns></returns> public static double lcg_value() => MTGenerator.NextDouble();
public static int mt_rand(int min, int max) // TODO: long min, long max, mt_getrandmax
{
return((min < max) ? MTGenerator.Next(min, max) : MTGenerator.Next(max, min));
}