in computer science, usually, the mathematical definition is used. very often, the comparison is written "==" (and the assignment, the act of giving a value, is written as "=", or ":="). in object-oriented languages, or languages which have pointers, there is an additional problem. those languages contain references (which are in fact pointers). if two such references do not reference exactly the same object, then they are different and "a == b" will be false in this case.