18,446,744,073,709,551,615 This number mentioned, 18,446,744,073,709,551,615, is actually 2^64 − 1. The important thing here is that 2^64-1 is essentially 0-based 2^64. The first digit of an unsigned integer is 0, not 1. So if the maximum value is 1, it has two possible values: 0, or 1 (2). Let’s look at 2^64 – 1 in … Read more
You could check whether the content of two functions is exactly the same by comparing the result of calling toString on them var foo = function() { a = 1; }; var bar = function() { a = 1; }; alert(foo.toString() == bar.toString()); That will, however, fail if there is but one character that is … Read more
For a bit of facts here is the relevant text from the specifications Equality operator (==,!=) Pointers to objects of the same type can be compared for equality with the ‘intuitive’ expected results: From § 5.10 of the C++11 standard: Pointers of the same type (after pointer conversions) can be compared for equality. Two pointers … Read more
I want to know which approach is a better in terms of performance and maintainability. As always, you have the tools to figure it out. Code both possible solutions and make them race. The one that wins is the winner, you don’t need anyone here to answer this particular question. About maintenance, the solution that … Read more
The answer, it turns out, is to use LanguagePrimitives.PhysicalEquality: let isSameObject = LanguagePrimitives.PhysicalEquality let a = [1; 2; 3] let b = [1; 2; 3] let a’ = a printfn “%A” (isSameObject a b) // Prints “false” printfn “%A” (isSameObject a a’) // Prints “true” There was precisely one question I could find on Stack … Read more
As of iOS 5 you can just use isEqual: (see comments) Try [indexPath1 compare: indexPath2] == NSOrderedSame. Maybe you found a bug in NSIndexPath. If you try to create a new NSIndexPath with a path that already exists you should get that one instead. So isEqual: probably just compares the pointers and not the actual … Read more
Here is an alternate solution, though perhaps a bit verbose: func sameStringSlice(x, y []string) bool { if len(x) != len(y) { return false } // create a map of string -> int diff := make(map[string]int, len(x)) for _, _x := range x { // 0 value for int is 0, so just increment a counter … Read more
Referential Equality Java In Java, the default implementation of equals compares the variable’s reference, which is what == always does: The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and … Read more
String s = “”; String s2 = someUserInputVariale.toLowercase(); // where the user entered in “” Something like that would cause s == s2 to evaluate to false. Lots of code sill create new Strings without exposing the call to new String().
Thanks to @CodingPickle comment, I provide the following from the Go Programming Language Specification The equality operators == and != apply to operands that are comparable. Regarding interface{}s and structs: Interface values are comparable. Two interface values are equal if they have identical dynamic types and equal dynamic values or if both have value nil. … Read more