equality

If I have three or more objects like so: a = 4 b = 4 c = 4 d = 2 what would be a clean ruby-style way of determining whether they are all equal? Any bespoke methods for running equality tests on three or more elements? I suppose I could do something like this: arrays = [a,b,c,d].map{|x| [x]} arrays.first == arrays.reduce(:&) ? true : false which appears to work, but feels sort of ham handed, and might be difficult for other developers to read. kipar [a,b,c,d].any?{|x| x != a} or array.any?{|x| x != array.first} Alternatively, the #all? method may read more intuitively for some: array.all? {|x|

I want to check this: if ( typeof myVar != "undefined" && myVar != null ) ... In other words, I want to check if a variable has a defined value (including 0 or an empty string), but not undefined or null, which I interpret as valueless. Do I have to do the two-part check each time or is there a handy shortcut? If you know the context of myVar , you should be able to do this: if (this.myVar != null) { ... } If you want to allow 0 and "" as valid values and you want to cover the case of the variable might not even be delcared, but don't consider null a valid value, then you have to specifically

This question already has an answer here: how to determine if 2 dates object equals each other? [duplicate] 3 answers I have been messing around with JSFiddle to solve this problem in FreeCodeCamp. When I use Date as a string (i.e., no "new"): Case 1: function isSameDay (dtFrom, dtTo) { return dtFrom == dtTo } let today = Date() let tomorrow = Date() console.log(today) console.log(tomorrow) console.log(isSameDay(today, tomorrow)) isSameDay returns true . However when I use Date as a constructor (with "new"): Case 2: function isSameDay (dtFrom, dtTo) { return dtFrom == dtTo } let today = new

How do you test multiple values for equality in one line? Basically I want to do if (val1 == val2 == val3 == ... valN) but in VB.Net. If val1 = valN AndAlso val2 = valN AndAlso ... Then End If This can get cumbersome when testing more than a few values. If you have a lot of values to test and do this very often, you could write you a helper like this: Public Function AllTheSame(ByVal ParamArray values() As Object) As Boolean For index As Integer = 1 To values.Length - 1 If values(0) <> values(index) Then Return False Next Return True End Function <Fact()> Public Sub testAllTheSame() Assert

Why won't this compile? fn isPalindrome<T>(v: Vec<T>) -> bool { return v.reverse() == v; } I get error[E0308]: mismatched types --> src/main.rs:2:25 | 2 | return v.reverse() == v; | ^ expected (), found struct `std::vec::Vec` | = note: expected type `()` found type `std::vec::Vec<T>` Read up on the documentation for the function you are using: Reverse the order of elements in a slice, in place. Or check the function signature: fn reverse(&mut self) The return value of the method is the unit type, an empty tuple () . You can't compare that against a vector. Stylistically, Rust uses 4 space

In F#, the equality operator (=) is generally extensional, rather than intensional. That's great! Unfortunately, it appears to me that F# does not use pointer equality to short-cut these extensional comparisons. For instance, this code: type Z = MT | NMT of Z ref // create a Z: let a = ref MT // make it point to itself: a := NMT a // check to see whether it's equal to itself: printf "a = a: %A\n" (a = a) ... gives me a big fat segmentation fault[*], despite the fact that 'a' and 'a' both evaluate to the same reference. That's not so great. Other functional languages (e.g. PLT Scheme) get this