According to this java.sun page == is the equality comparison operator for floating point numbers in Java. However, when I type this code: if(sectionID == currentSectionID) into my editor and run static analysis, I get: “JAVA0078 Floating point values compared with ==” What is wrong with using == to compare floating point values? What is … Read more
I would like to check whether an object (e.g. someObject) is assignable (cast-able) to a variable of another type (e.g. SpecifiedType). In Java, I can write: someObject instanceof SpecifiedType A related question is finding whether the runtime type of an object is equal to a another type. In Java, I can write: someObject.getClass().equals(SpecifiedType.class) How can … Read more
What is the difference between these two lines of code: if not x == ‘val’: and if x != ‘val’: Is one more efficient than the other? Would it be better to use if x == ‘val’: pass else: 7 Answers 7
Consider the following example: class Quirky { public static void main(String[] args) { int x = 1; int y = 3; System.out.println(x == (x = y)); // false x = 1; // reset System.out.println((x = y) == x); // true } } I’m not sure if there is an item in the Java Language Specification … Read more
I want my Food class to be able to test whenever it is equal to another instance of Food. I will later use it against a List, and I want to use its List.Contains() method. Should I implement IEquatable<Food> or just override Object.Equals()? From MSDN: This method determines equality by using the default equality comparer, … Read more
When comparing arrays in Java, are there any differences between the following 2 statements? Object[] array1, array2; array1.equals(array2); Arrays.equals(array1, array2); And if so, what are they? 8 Answers 8
How do you compare two instances of structs for equality in standard C? 11 Answers 11
How do you properly override isEqual: in Objective-C? The “catch” seems to be that if two objects are equal (as determined by the isEqual: method), they must have the same hash value. The Introspection section of the Cocoa Fundamentals Guide does have an example on how to override isEqual:, copied as follows, for a class … Read more
Is it guaranteed that False == 0 and True == 1, in Python (assuming that they are not reassigned by the user)? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (both existing and, likely, future ones)? 0 == False # … Read more
I’m learning about operator overloading in C++, and I see that == and != are simply some special functions which can be customized for user-defined types. My concern is, though, why are there two separate definitions needed? I thought that if a == b is true, then a != b is automatically false, and vice … Read more
