Using Lambda to filter by object member and a second integer array

Question

I have an array of integers:

int[] numbers = { 1, 3, 5, 7, 9 };

I also have an array of a custom object that contains an integer. I want to filter the array of custom objects using Lambda to only those matching integers in the numbers array above.

public class SomeStruct
{
    public int MyNumber;
}

ArrayOfSomeStruct = ArrayOfSomeStruct
    .Where(m = m.MyNumber is contained in numbers array);

How is this done?

Change numbers into a HashSet and then use HashSet.Contains in the Where. — MineR, Jul 18 '18 at 00:11

score 3 · Answer 1 · answered Jul 18 '18 at 01:13

Following your example, I've created an example here

This is the code that would get the elements of your array if their number is contained within your "number" variable.

ArrayOfSomeStruct = ArrayOfSomeStruct.Where(x => numbers.Contains(x.MyNumber)).ToArray();

score 3 · Accepted Answer · answered Jul 18 '18 at 01:15

3

Seems like you want something like that:

int[] numbers = { 1, 3, 5, 7, 9 };
var numbersSet = numbers.ToHashset(); // for performance reason
var filtered = arrayOfSomeStruct.Where(e => numbersSet.Contains(e.MyNumber));

answered Jul 18 '18 at 01:15

Christian Gollhardt

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Using Lambda to filter by object member and a second integer array

2 Answers2