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c#set
Brian Genisio
Brian Genisio

Reputation: 48137

Generating sets of integers in C#

In F#, you can generate a set of numbers, just by saying [1..100].

I want to do something similar in C#. This is what I have come up with so far:

public static int[] To(this int start, int end)
{
    var result = new List<int>();
    for(int i = start; i <= end; i++)
        result.Add(i);
    return result.ToArray();
}

By doing this, I can now create a set by saying 1.To(100)

Unfortunately, this is not nearly as readable as [1..100]. Has anyone come up with a better way to do this in C#? Is it more readable if it is lowercase? 1.to(100), for instance? Or, is "To" a bad word? Is something like 1.Through(100) more readable?

Just looking for some thoughts. Has anyone else come up with a more elegant solution?

EDIT: After reading the responses, I have re-written my To method using the range:

public static int[] To(this int start, int end)
{
    return Enumerable.Range(start, end - start + 1).ToArray();
}

I am still looking for thoughts on the readability of 1.To(100)

Upvotes: 3

Views: 2280

Answers (5)

Christoffer Lette
Christoffer Lette

Reputation: 14816

I like the idea of using To. The alternative Enumerable.Range has a subtle flaw imo. The second parameter is not the value of the last element, it is the length of the enumeration. This is what I've done in the past:

public IEnumerable<int> To(this int start, int stop)
{
  while (start <= stop)
    yield return start++;
}

EDIT: If you want the result as an int[], just add .ToArray():

int[] theSet = 1.To(100).ToArray();

Upvotes: 5

plinth
plinth

Reputation: 49189

I think you're worried too much that the language doesn't exactly express the particular syntactic thing that you want.

The way I see it, extension methods are a nice bit of sugar, but I wonder if you're really using it so much to justify the "surprise" of the extension method.

Within the domain of the language C#, it is more appropriate to spell out via the method name what you're trying to do. This feels more like Ruby than C#. This feels more like it wants to be in class by itself, especially if you wanted to add ranges with skip patterns (ie, the numbers from 1 to 10 by threes). I think that

public class RangedArray {
    public static int[] Generate(int from, into to, int by=1) { /* ... */ }
}

is a perfectly acceptable to express this in C#.

Upvotes: 0

Brian Rudolph
Brian Rudolph

Reputation: 6318

Your answer to your own question is fine. Just don't use a List if you are concerned about performance. Constructing a list and constantly expanding it is foolish. Just construct an array of the appropriate size. Use an extension method

public static int[] To(this int num)
    {
        //do work
    }

Upvotes: 0

lc.
lc.

Reputation: 116498

I think something like Set(1,100) or IntSequence(1,100) is easier to read than using an extension method.

Personal opinion though...

Upvotes: 0

terjetyl
terjetyl

Reputation: 9565

Enumerable.Range(1, 100);

Upvotes: 8

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