Count elements with int < 5 in List

Question

I have a List<int> and need to count how many elements with (value < 5) it has - how do I do this?

Yeesh! Someone spent a bunch of time downvoting 4 answers below. — p.campbell, Nov 26 '11 at 17:09
@p.campbell - Yeah, whomever it was took offence to the extraneous `Where`. — Oded, Nov 26 '11 at 18:28
possible duplicate of [Get item count of a list<> using Linq](http://stackoverflow.com/questions/3853010/get-item-count-of-a-list-using-linq) — Raymond Chen, Nov 30 '11 at 14:38

score 62 · Accepted Answer · answered Nov 26 '11 at 16:15

62

Count() has an overload accepting Predicate<T>:

int count = list.Count(x => x < 5);

See MSDN

answered Nov 26 '11 at 16:15

abatishchev

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George Duckett · Answer 2 · 2011-11-26T16:21:49.343

37

Unlike other answers, this does it in one method call using this overload of the count extension method:

using System.Linq;

...

var count = list.Count(x => x < 5);

Note that since linq extension methods are defined in the System.Linq namespace you might need to add a using statement, and reference to System.Core if it's not already there (it should be).

See also: Extension methods defined by the Enumerable class.

edited Nov 26 '11 at 16:21

answered Nov 26 '11 at 16:14

George Duckett

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2

+1 because you were one minute earlier than the accepted answer of abatischchev ;) – Abel Nov 29 '11 at 17:25

score 18 · Answer 3 · answered Nov 26 '11 at 16:14

18

The shortest option:

myList.Count(v => v < 5);

This would also do:

myList.Where(v => v < 5).Count();

answered Nov 26 '11 at 16:14

Oded

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+1 I actually really like the later method here as they are pretty much equivalent performance wise and I think it's a little clearer what's going on here. – ForbesLindesay Nov 30 '11 at 04:20

score 8 · Answer 4 · answered Nov 26 '11 at 16:15

8

int count = list.Count(i => i < 5);

answered Nov 26 '11 at 16:15

Matthew Abbott

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score 6 · Answer 5 · answered Nov 26 '11 at 16:13

6

List<int> list = ...
int count = list.Where(x => x < 5).Count();

answered Nov 26 '11 at 16:13

Darin Dimitrov

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score 6 · Answer 6 · answered Nov 26 '11 at 16:15

6

Try -

var test = new List<int>();
test.Add(1);
test.Add(6);
var result =  test.Count(i => i < 5);

answered Nov 26 '11 at 16:15

ipr101

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score 4 · Answer 7 · answered Nov 26 '11 at 16:14

4

Something like this:

var count = myList.Where(x => x < 5).Count();

answered Nov 26 '11 at 16:14

JohnD

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score 4 · Answer 8 · answered Nov 26 '11 at 16:15

4

list.Where(x => x < 5).Count()

answered Nov 26 '11 at 16:15

akoso

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score 3 · Answer 9 · answered Nov 26 '11 at 16:14

3

Try this:

int c = myList.Where(x=>x<5).Count();

answered Nov 26 '11 at 16:14

p.campbell

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score 2 · Answer 10 · edited Apr 22 '12 at 20:15

2

int c = 0;
for (i = 0; i > list.Count; i++)
{
    // The "for" is check all elements that in list.
    if (list[i] < 5)
    {
        c = c + 1; // If the element is smaller than 5
    }
}

edited Apr 22 '12 at 20:15

abatishchev

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answered Nov 30 '11 at 14:33

kpratama

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+1 For being the only answer that doesn't use LINQ. Although I would have preferred use of "foreach" instead of "for". Even better would be a generalized method that has a predicate as the parameter and can then be invoked using lambda notation. – RenniePet Mar 24 '14 at 10:47

Count elements with int < 5 in List

10 Answers10