C# -Random Numbers and Enumrable

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C# -Random Numbers and Enumrable

Shervan360 1,661

Hi,

Could you please explain the below query? What is the relationship between a list, s, and random numbers?

Is the Range method simulated for loop here? Do we use the Range method instead of for loop?

Isn't it better to discard the s variable in the Select method?

I really appreciate any help you can provide.

  static void Main(string[] args)
        {
            var rand = new Random();
            IEnumerable<int> list = Enumerable.Range(100, 5); // Is this simulate for loop?
            var r = list.Select(s => rand.Next(-20, 31)).ToArray(); // I'm confused here.
            foreach (var item in r)
            {
                Console.WriteLine(item);
            }
        }

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Answer 1

Bruce (SqlWork.com) 77,686 Volunteer Moderator

Range(100,5) creates a collection of 5 ints starting at 100 = [100,101,102,103,104]

Next(-20,31) return a random number between -20 and 31

Select uses a lambda with the parameter of the collection type

so r = will be an int array of 5 random numbers between -20 and 31

in the sample code the values of list are not used, only the count, so not sure why a starting value of 100 instead of 0 or 1 was specified.

Shervan360 1,661 Reputation points

2023-02-08T18:31:57.43+00:00

The code is from the following link: (although I changed the code a little for learning)

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/patterns#var-pattern
Jack J Jun 25,296 Reputation points

2023-02-09T02:01:38.7333333+00:00
@Shervan360, Welcome to Microsoft Q&A, I think Bruce's explanation is almost correct. As the addition for the question Isn't it better to discard the s variable in the Select method?, If you don't want to use lambda or the s variable to generate the random, you could try to use the for loop to replace it.

int[] arr = new int[5]; for (int i = 0; i < list.Count(); i++) { arr[i] = rand.Next(-20, 31); }

The following code is related to the count of list instead of the specific element of the list, so here s variable is not used in the Select method.

var r = list.Select(s => rand.Next(-20, 31)).ToArray();
Jack J Jun 25,296 Reputation points

2023-02-14T08:05:13.6233333+00:00

@Shervan360, is any update? Do you have any questions now?

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C# -Random Numbers and Enumrable

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