我如何在c#中生成一个随机的8个字符的字母数字字符串?


当前回答

您只需使用程序集SRVTextToImage。并编写下面的代码生成随机字符串。

CaptchaRandomImage c1 = new CaptchaRandomImage();
            string text = c1.GetRandomString(8);

它主要用于实现验证码。但对你来说也一样。希望能有所帮助。

其他回答

I was looking for a more specific answer, where I want to control the format of the random string and came across this post. For example: license plates (of cars) have a specific format (per country) and I wanted to created random license plates. I decided to write my own extension method of Random for this. (this is in order to reuse the same Random object, as you could have doubles in multi-threading scenarios). I created a gist (https://gist.github.com/SamVanhoutte/808845ca78b9c041e928), but will also copy the extension class here:

void Main()
{
    Random rnd = new Random();
    rnd.GetString("1-###-000").Dump();
}

public static class RandomExtensions
{
    public static string GetString(this Random random, string format)
    {
        // Based on http://stackoverflow.com/questions/1344221/how-can-i-generate-random-alphanumeric-strings-in-c
        // Added logic to specify the format of the random string (# will be random string, 0 will be random numeric, other characters remain)
        StringBuilder result = new StringBuilder();
        for(int formatIndex = 0; formatIndex < format.Length ; formatIndex++)
        {
            switch(format.ToUpper()[formatIndex])
            {
                case '0': result.Append(getRandomNumeric(random)); break;
                case '#': result.Append(getRandomCharacter(random)); break;
                default : result.Append(format[formatIndex]); break;
            }
        }
        return result.ToString();
    }

    private static char getRandomCharacter(Random random)
    {
        string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        return chars[random.Next(chars.Length)];
    }

    private static char getRandomNumeric(Random random)
    {
        string nums = "0123456789";
        return nums[random.Next(nums.Length)];
    }
}

问:为什么我要浪费时间使用Enumerable ?范围,而不是输入“ABCDEFGHJKLMNOPQRSTUVWXYZ0123456789”?

using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
    public static void Main()
    {
        var randomCharacters = GetRandomCharacters(8, true);
        Console.WriteLine(new string(randomCharacters.ToArray()));
    }

    private static List<char> getAvailableRandomCharacters(bool includeLowerCase)
    {
        var integers = Enumerable.Empty<int>();
        integers = integers.Concat(Enumerable.Range('A', 26));
        integers = integers.Concat(Enumerable.Range('0', 10));

        if ( includeLowerCase )
            integers = integers.Concat(Enumerable.Range('a', 26));

        return integers.Select(i => (char)i).ToList();
    }

    public static IEnumerable<char> GetRandomCharacters(int count, bool includeLowerCase)
    {
        var characters = getAvailableRandomCharacters(includeLowerCase);
        var random = new Random();
        var result = Enumerable.Range(0, count)
            .Select(_ => characters[random.Next(characters.Count)]);

        return result;
    }
}

答案:魔术弦不好。有没有人注意到在我的字符串顶部没有“I”?我妈妈教我不要用魔法弦就是因为这个原因……

注意事项1:正如许多像@dtb这样的人所说,不要使用系统。随机的,如果你需要密码安全…

注2:这个答案不是最有效或最短的,但我想用空间把答案和问题分开。我回答这个问题的目的,更多的是为了警告人们不要使用神奇的字符串,而不是提供一个花哨的创新答案。

如果你的值不是完全随机的,但实际上可能依赖于某些东西——你可以计算出“某个东西”的md5或sha1哈希,然后将其截断为你想要的任何长度。

你也可以生成和截断一个guid。

只需一行代码member . generatepassword()就可以做到这一点。

这里有一个相同的演示。

Eric J.写的代码很潦草(很明显这是6年前写的……他今天可能不会写那个代码),甚至还有一些问题。

与目前提出的一些替代方案不同,这个方案在密码学上是合理的。

不真实的…在密码中有一个偏差(正如在注释中所写的那样),bcdefgh比其他的更有可能(a不是,因为通过GetNonZeroBytes,它不会生成值为0的字节,因此a的偏差由它平衡),所以它在密码学上并不可靠。

这应该可以纠正所有的问题。

public static string GetUniqueKey(int size = 6, string chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
{
    using (var crypto = new RNGCryptoServiceProvider())
    {
        var data = new byte[size];

        // If chars.Length isn't a power of 2 then there is a bias if
        // we simply use the modulus operator. The first characters of
        // chars will be more probable than the last ones.

        // buffer used if we encounter an unusable random byte. We will
        // regenerate it in this buffer
        byte[] smallBuffer = null;

        // Maximum random number that can be used without introducing a
        // bias
        int maxRandom = byte.MaxValue - ((byte.MaxValue + 1) % chars.Length);

        crypto.GetBytes(data);

        var result = new char[size];

        for (int i = 0; i < size; i++)
        {
            byte v = data[i];

            while (v > maxRandom)
            {
                if (smallBuffer == null)
                {
                    smallBuffer = new byte[1];
                }

                crypto.GetBytes(smallBuffer);
                v = smallBuffer[0];
            }

            result[i] = chars[v % chars.Length];
        }

        return new string(result);
    }
}