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Sometimes, particularly in object-oriented programming, the comparison raises questions of data types and inheritance, equality, and identity. It is often necessary to distinguish between: two different objects of the same type, e.g., two hands; two objects being equal but distinct, e.g., two $10 banknotes
This is the test cases page for the module Module:If any equal. Results of the test cases. ... -- Example unit test. function p: test_live self: preprocess_equals ...
Many object-oriented programming languages have a three-way comparison function, which performs a three-way comparison between the object and another given object. For example, in Java , any class that implements the Comparable interface has a compareTo method which either returns a negative integer, zero, or a positive integer, or throws a ...
Duck typing is similar to, but distinct from, structural typing.Structural typing is a static typing system that determines type compatibility and equivalence by a type's structure, whereas duck typing is dynamic and determines type compatibility by only that part of a type's structure that is accessed during runtime.
The same distinction holds for comparing objects for equality: most basically there is a difference between identity (same object) and equality (same value), corresponding to shallow equality and (1 level) deep equality of two object references, but then further whether equality means comparing only the fields of the object in question or ...
In programming languages with a built-in Boolean data type, such as Pascal, C, Python or Java, the comparison operators such as > and ≠ are usually defined to return a Boolean value. Conditional and iterative commands may be defined to test Boolean-valued expressions.
Python 3.8 introduced assignment expressions, but uses the walrus operator := instead of a regular equal sign (=) to avoid bugs which simply confuse == with =. [13] Another disadvantage appears in C++ when comparing non-basic types as the == is an operator and there may not be a suitable overloaded operator function defined.
A notorious example for a bad idea was the choice of the equal sign to denote assignment. It goes back to Fortran in 1957 [a] and has blindly been copied by armies of language designers. Why is it a bad idea? Because it overthrows a century old tradition to let “=” denote a comparison for equality, a predicate which is either true or false.