Generate number sequence with step size in linq

I need to generate a sequence of numbers using C# linq. Here is how I have done it using for loop.

int startingValue = 1;
int endValue = 13;
int increment = 5;
for (int i = startingValue; i <= endValue; i += increment) {
Console.WriteLine(i);
}


Console.WriteLine(i)

yield return i

IEnumerable<int>

4 Answers
4

If you want to mimic your procedural code, you can use TakeWhile:

Enumerable.Range(0, int.MaxValue).
Select(i => startValue + (i * increment)).
TakeWhile(i => i <= endValue);


But this is to my opinion worse in terms of performance and readability.

Not everthing has to be done in LINQ to be usasable like Linq, you can stick very close to your original:

IEnumerable<int> CustomSequence(int startingValue = 1, int endValue = 13, int increment = 5)
{
for (int i = startingValue; i <= endValue; i += increment)
{
yield return i;
}
}


Call it like

var numbers = CustomSequence();


or do any further LINQ on it:

var firstTenEvenNumbers = CustomSequence().Where(n => n % 2 == 0).Take(1).ToList();


Try Enumerable.Range in order to emulate for loop:

for

int startingValue = 1;
int endValue = 13;
int increment = 5;

var result = Enumerable
.Range(0, (endValue - startingValue) / increment + 1)
.Select(i => startingValue + increment * i);

Console.Write(string.Join(", ", result));


Outcome:

1, 6, 11


Seems wasteful but the best I can think of is something like this:

int startingValue = 1;
int endValue = 13;
int increment = 5;
var sequence = Enumerable.Range(startingValue,(endingValue-startingValue)+1)
.Where(i=>i%increment == startingValue%increment);


Which is hopefully easy to follow. Logically, all of the values produced by your for loop are congruent to the startingValue modulo increment. So we just generate all of the numbers between startingValue and endingValue (inclusive) and then filter them based on that observation.

for

startingValue

increment

startingValue

endingValue

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.