C#, check whether integer array has negative numbers in it

Question

I have a array int[] numArray . I want to know is there any straight forward way to just check whether array has negative numbers in it ?

If there is no direct method even linq will do . I am bit new to linq . Can anyone suggest ?

Solution 1

You could use Any:

bool containsNegative = numArray.Any(i => i < 0)

Or

bool containsNegative = numArray.Min() < 0;

---

int[] negativeNumbers = numArray.Where(i => i < 0).ToArray();

Solution 2

If you're open to using LINQ:

var containsNegatives = numArray.Any(n => n < 0);

Or, if you want to do it the "old fashioned" way...you just have to loop:

var containsNegatives = false;

foreach(var n in numArray)
{
    if(n < 0)
    {
        containsNegatives = true;
        break;
    }
}

And if you really want to get fancy, you could turn that into an Extension method:

public static class EnumerableExtensions
{
    public static bool ContainsNegatives(this IEnumerable<int> numbers)
    {
        foreach(n in numbers)
        {
            if(n < 0) return true;
        }

        return false;
    }
}

And call it from your code like:

var containsNegatives = numArray.ContainsNegatives();

Solution 3

var negativeExist = numArray.Any(a => a < 0);

Comments

[gor]

Or you could wrap old fashioned way in Extension method, and use it like LINQ.

[Justin Niessner]

@gor - Haha...funny that you made the comment while I was adding that to the answer. Good idea.

[Kuntady Nithesh]

How do i retrieve all negative numbers through linq ?

[Bala R]

there is no need to loop through all items. You can return when you find the first negative item.

[Alan]

@IAbstractDownvoteFactory: Any() looks like a better solution than Min(), since Any() returns true upon finding the first negative element, while Min() always loops through the entire array. You might want to indicate this in your answer.

[Rune FS]

@BalaR which is why the code I've posted exits after finding the first

[Bala R]

Ah, I missed the !res in the loop contition. Not used to looking conditions like that up there.