I have a class MyClass, which contains two member variables foo and bar: class MyClass: def __init__(self, foo, bar): self.foo = foo self.bar = bar I have two instances of this class, each of which has identical values for foo and bar: x = MyClass(‘foo’, ‘bar’) y = MyClass(‘foo’, ‘bar’) However, when I compare them … Read more
I have a double in Java and I want to check if it is NaN. What is the best way to do this? 7 Answers 7
When writing custom classes it is often important to allow equivalence by means of the == and != operators. In Python, this is made possible by implementing the __eq__ and __ne__ special methods, respectively. The easiest way I’ve found to do this is the following method: class Foo: def __init__(self, item): self.item = item def … Read more
I am trying to understand the difference between these four methods. I know by default that == calls the method equal? which returns true when both operands refer to exactly the same object. === by default also calls == which calls equal?… okay, so if all these three methods are not overridden, then I guess … Read more
This question already has answers here: Why does comparing strings using either ‘==’ or ‘is’ sometimes produce a different result? (15 answers) Closed 8 years ago. I noticed a Python script I was writing was acting squirrelly, and traced it to an infinite loop, where the loop condition was while line is not ”. Running … Read more
This question’s answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. My Google-fu has failed me. In Python, are the following two tests for equality equivalent? n = 5 # Test one. if n == 5: print ‘Yay!’ # Test two. if n … Read more
This question’s answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. I’ve been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed … Read more
I wanted to clarify if I understand this correctly: == is a reference comparison, i.e. both objects point to the same memory location .equals() evaluates to the comparison of values in the objects 25 s 25 In general, the answer to your question is “yes”, but… .equals(…) will only compare what it is written to … Read more
How can I check for null values in JavaScript? I wrote the code below but it didn’t work. if (pass == null || cpass == null || email == null || cemail == null || user == null) { alert(“fill all columns”); return false; } And how can I find errors in my JavaScript programs? … Read more
Two string variables are set to the same value. s1 == s2 always returns True, but s1 is s2 sometimes returns False. If I open my Python interpreter and do the same is comparison, it succeeds: >>> s1 = ‘text’ >>> s2 = ‘text’ >>> s1 is s2 True Why is this? 1 15
