Generating a 4–8 digit random number

Question

Random random = new Random();
int password = random.Next(10000);

This generates 2-digit and 3-digit numbers also. How do I generate a 4–8 digit random number in C#?

see the following link: http://stackoverflow.com/questions/13539974/random-number-generator-c-sharp[enter link description here][1] [1]: http://stackoverflow.com/questions/13539974/random-number-generator-c-sharp — Rayhan.iit.du, Jun 18 '13 at 03:38
For your purposes, is **0004** a 4-digit number? Is **00000008** an 8-digit number? Does it matter that those are included? — doppelgreener, Jun 18 '13 at 03:57

score 34 · Accepted Answer · answered Jun 18 '13 at 03:34

34

Start at the smallest 4-digit number, end at the smallest 9-digit number (exclusive):

int password = random.Next(1000, 100000000);

answered Jun 18 '13 at 03:34

Ry-

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score 3 · Answer 2 · answered Jun 18 '13 at 03:50

3

You could also make a method:

public static int GetRandom(int minDigits, int maxDigits)
{
    if (minDigits < 1 || minDigits > maxDigits)
        throw new ArgumentOutOfRangeException();

    return (int)random.Next(Math.Pow(10, minDigits - 1), Math.Pow(10, maxDigits - 1));
}

answered Jun 18 '13 at 03:50

AgentFire

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You could, but why would you ever do that? – Jun 18 '13 at 05:42

Pinch · Answer 3 · 2014-12-30T20:32:53.170

3

To cover all your bases (numbers under 1000 such as 0002)

Random RandomPIN = new Random();
var RandomPINResult = RandomPIN.Next(0, 9999).ToString();
RandomPINResult = RandomPINResult.PadLeft(4, '0');

edited Dec 30 '14 at 20:32

answered May 21 '14 at 22:06

Pinch

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1

Why not: `Random RandomPIN = new Random(); var RandomPINResult = RandomEASPIN.Next(0, 9999).ToString("D4");` – Mir Dec 29 '14 at 19:38

score 2 · Answer 4 · answered Jun 10 '16 at 14:07

2

new Random(Guid.NewGuid().GetHashCode()).Next(0, 9999).ToString("D4")

answered Jun 10 '16 at 14:07

Vladimir G. Nosov

21
2

It uses the classical random value, but the author was aware that a seed is needed to get real random values. So the next step is just to generate an int from an interval and make sure it's formatted with pre-pending (pad left) zeros (4 digit length). – baHI Mar 27 '17 at 10:52

Generating a 4–8 digit random number

4 Answers4