finding closest value in an array

Question

``` int[] array = new int[5]{5,7,8,15,20}; int TargetNumber = 13; ``` For a target number, I want to find the closest number in an array. For example, when the target number is 13, the closest number to it in the array above is 15. How would I accomplish that programmatically in C#?

Accepted Answer

EDIT: Have adjusted the queries below to convert to using `long` arithmetic, so that we avoid overflow issues.

I would probably use MoreLINQ's `MinBy` method:

```
var nearest = array.MinBy(x => Math.Abs((long) x - targetNumber));
```

Or you could just use:

```
var nearest = array.OrderBy(x => Math.Abs((long) x - targetNumber)).First();
```

... but that will sort the whole collection, which you really don't need. It won't make much difference for a small array, admittedly... but it just doesn't feel quite right, compared with describing what you're actually trying to do: find the element with the minimum value according to some function.

Note that both of these will fail if the array is empty, so you should check for that first.

finding closest value in an array

Solution

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