Random strings. In C# we generate random strings with a built-in method. This method, found in System.IO, generates random strings with high quality randomness. It is easy to use.
This problem can be approached in many ways, but the approaches that use the Random class have weaknesses. We can get repeating numbers due to the time-based seed value.
Example code. The Path.GetRandomFileName method is an effective way of generating strings. It uses RNGCryptoServiceProvider for better randomness, but is limited to 11 characters.
Part 1 We call the Path.GetRandomFileName method from the System.IO namespace.
Part 2 The string contains one period which is not random. We remove the period in the Replace call.
Part 3 We invoke the RandomUtil.GetRandomString method 2 times to test that its output seems random.
using System;
using System.IO;
/// <summary>/// Random string generators./// </summary>
static class RandomUtil
{
/// <summary>/// Get random string of 11 characters./// </summary>/// <returns>Random string.</returns>
public static string GetRandomString()
{
// Part 1: use GetRandomFileName.
string path = Path.GetRandomFileName();
// Part 2: remove period.
path = path.Replace(".", "");
return path;
}
}
class Program
{
static void Main()
{
// Part 3: test the random string method.
Console.WriteLine(RandomUtil.GetRandomString());
Console.WriteLine(RandomUtil.GetRandomString());
}
}wzp3t2j5a2o
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Cryptographic. GetRandomFileName uses RNGCryptoServiceProvider—this logic is cryptographic-strength. GetBytes is invoked internally and it returns random bytes.
And These random bytes are then used with bitwise ANDs to fill the result value.
Summary. With the Path class, we can obtain a random string. This method has a limitation on the length of the result, which means you may need to call it more than once or truncate the result.
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This page was last updated on Feb 9, 2025 (rewrite).