how to check if List<string> exists all values in other List<string>

Question

I'm trying to figure out how to check if all values match other List values.

Example:

List<string> foo = new List<string>() {"banana","apple","coconut"}
List<string> bar = new List<string>() {"banana","apple","coconut","mango", "lemon"}

if every foo list item exists in bar then return true and if at least one is not in foo list then return false. AND if Example:

List<string> foo = new List<string>() {"banana",}
List<string> bar = new List<string>() {"banana","apple","coconut","mango", "lemon"}

should return true

AND if Example:

List<string> foo = new List<string>() {"banana","melon"}
List<string> bar = new List<string>() {"banana","apple","coconut","mango", "lemon"}

should return false

AND if Example:

List<string> foo = new List<string>() {"banana","apple","coconut","mango", "lemon"}
List<string> bar = new List<string>() {"banana"}

should return false

sory for all the changes. got to do this fast :D

Welcome. Those are different requirements, I don't think there's a clean way to have an all-in-one solution. What have you tried so far? — devsmn
– devsmn, Commented Dec 23, 2020 at 15:09
Have you thought about duplicates? eg. foo containing apple twice but bar only has 1 instance of apple? — Rand Random
– Rand Random, Commented Dec 23, 2020 at 15:17
"and if at least one is not in foo" did you mean "and if at least one is not in bar" — phuzi
– phuzi, Commented Dec 23, 2020 at 15:18

Amal Ps · Accepted Answer · 2020-12-26 08:32:59Z

In your case, I think you can use something like

 var resultBool = foo.All(x => bar.Any(y => x == y));

Here, we are comparing the lists by each value. if the foo has a string value which not present in the bar then the result will be false.

I think this will help you to find a solution.

List<string> foo = new List<string>() { "banana", "apple", "coconut" };
List<string> bar = new List<string>() { "banana", "apple", "coconut", "mango", "lemon" };
//true
var test1 = foo.All(x => bar.Any(y => x == y));

List<string> foo2 = new List<string>() { "banana", };
List<string> bar2 = new List<string>() { "banana", "apple", "coconut", "mango", "lemon" };
//true
var test2 = foo2.All(x => bar2.Any(y => x == y));

List<string> foo3 = new List<string>() { "banana", "melon" };
List<string> bar3 = new List<string>() { "banana", "apple", "coconut", "mango", "lemon" };
//false
var test3 = foo3.All(x => bar3.Any(y => x == y));

List<string> foo4 = new List<string>() { "banana", "apple", "coconut", "mango", "lemon" };
List<string> bar4 = new List<string>() { "banana" };
//false
var test4 = foo4.All(x => bar4.Any(y => x == y));

Happy coding :)

phuzi · Accepted Answer · 2020-12-23 15:15:41Z

1

This is actually fairly straight forward using Intersect()

foo.Intersect(bar).Count() == foo.Count()

edited Dec 23, 2020 at 15:15

answered Dec 23, 2020 at 15:03

phuzi

13.3k4 gold badges30 silver badges65 bronze badges

7 Comments

edvinas daubaris Over a year ago

yeah. it works for first two, but not quite what i'm looking.

phuzi Over a year ago

Given the updated requirements this should still be okay

phuzi Over a year ago

Why is it not what you are looking for. Could you explain? How can we answer if we don't have all the information.

Rand Random Over a year ago

Updated the example with randomizing the list, still seems good to me: dotnetfiddle.net/AyINza

phuzi Over a year ago

If it works for you, then please consider upvoting and accepting this answer. Thanks

|

Krishna Varma · Accepted Answer · 2020-12-23 15:30:08Z

0

try with Except

var matching = !foo.Except(bar).ToList().Any();

edited Dec 23, 2020 at 15:30

answered Dec 23, 2020 at 15:03

Krishna Varma

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3 Comments

phuzi Over a year ago

What if the items are out of order?

Rand Random Over a year ago

Yes, fails on randomizing the order - dotnetfiddle.net/f6tres (You may have to run it multiple times, for Test1RandomOrder to print false instead of true)

Rand Random Over a year ago

Yep works now with randomized list - dotnetfiddle.net/jBL1sd

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