How to Generate Six Unique Random Numbers in C#?

Avoid duplication: C# random number generator

Your code is designed to generate six random numbers between 1 and 49. However, these numbers may contain duplicates, which is unacceptable in a lottery-like scenario. To solve this problem, we will explore an efficient way to generate unique random numbers in C#.

Solution:

Store the generated numbers in a collection. Each time a new number is generated, check whether it already exists in the set. If it exists, continue generating another number until you find a unique number.

Here is a modified version of your code that implements this solution:

<code class="language-csharp">var randomNumbers = new List<int>();
var random = new Random();

while (randomNumbers.Count < 6)
{
    int randomNumber = random.Next(1, 50); // 生成1到49之间的随机数
    if (!randomNumbers.Contains(randomNumber))
    {
        randomNumbers.Add(randomNumber);
    }
}</code>

Alternatively, we can adopt the following strategy:

Shuffle the deck and choose method:

1. Create a sequence of numbers from 1 to 49.
2. Shuffle the sequence using a random function.
3. Select the first six numbers from the shuffled sequence.

Here is the code for this approach:

<code class="language-csharp">var rnd = new Random();
var randomNumbers = Enumerable.Range(1, 49).OrderBy(x => rnd.Next()).Take(6).ToList();</code>

This approach guarantees the generation of unique random numbers without the need for custom loops or additional checks for duplicates.

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