contains
Opposite of .contains (does not contain)
It seems that Luiggi Mendoza and joey rohan both already answered this, but I think it can be clarified a little. You can write it as a single if statement: if (inventory.contains(“bread”) && !inventory.contains(“water”)) { // do something }
how to check if a property value exists in array of objects in swift
You can filter the array like this: let results = objarray.filter { $0.id == 1 } that will return an array of elements matching the condition specified in the closure – in the above case, it will return an array containing all elements having the id property equal to 1. Since you need a boolean … Read more
Contains of HashSet in Python
Just use a set: >>> l = set() >>> l.add(1) >>> l.add(2) >>> 1 in l True >>> 34 in l False The same works for lists: >>> ll = [1,2,3] >>> 2 in ll True >>> 23 in ll False Edit: Note @bholagabbar’s comment below that the time complexity for in checks in lists … Read more
Check if a string exists in an array case insensitively
Xcode 8 • Swift 3 or later let list = [“kashif”] let word = “Kashif” if list.contains(where: {$0.caseInsensitiveCompare(word) == .orderedSame}) { print(true) // true } alternatively: if list.contains(where: {$0.compare(word, options: .caseInsensitive) == .orderedSame}) { print(true) // true } if you would like to know the position(s) of the element in the array (it might find … Read more
C++ implicit copy constructor for a class that contains other objects
Foo f1; Foo f2(f1); Yes this will do what you expect it to: The f2 copy constructor Foo::Foo(Foo const&) is called. This copy constructs its base class and then each member (recursively) If you define a class like this: class X: public Y { private: int m_a; char* m_b; Z m_c; }; The following methods … Read more
Add items to a collection if the collection does NOT already contain it by comparing a property of the items?
You start by finding which elements are not already in the collection: var newItems = DownloadedItems.Where(x => !CurrentCollection.Any(y => x.bar == y.bar)); And then just add them: foreach(var item in newItems) { CurrentCollection.Add(item); } Note that the first operation may have quadratic complexity if the size of DownloadedItems is close to the size of CurrentCollection. … Read more
What does Collection.Contains() use to check for existing objects?
List<T>.Contains uses EqualityComparer<T>.Default, which in turn uses IEquatable<T> if the type implements it, or object.Equals otherwise. You could just implement IEquatable<T> but it’s a good idea to override object.Equals if you do so, and a very good idea to override GetHashCode() if you do that: public class SomeIDdClass : IEquatable<SomeIDdClass> { private readonly int _id; … Read more
What is the linq equivalent to the SQL IN operator
.Contains var resultset = from x in collection where new[] {2,3,4,5}.Contains(x) select x Of course, with your simple problem, you could have something like: var resultset = from x in collection where x >= 2 && x <= 5 select x
Check if element is in the list (contains)
You can use std::find bool found = (std::find(my_list.begin(), my_list.end(), my_var) != my_list.end()); You need to include <algorithm>. It should work on standard containers, vectors lists, etc…