Relational operator

In computer science, a relational operator is a programming language construct or operator that tests or defines some kind of relation between two entities. These include numerical equality (e.g., 5 = 5) and inequalities (e.g., 4 ≥ 3).

In programming languages that include a distinct boolean data type in their type system, like Pascal, Ada or Java, these operators usually evaluate to true or false, depending on whether the conditional relationship between the two operands holds or not. In languages such as C, relational operators return the integers 0 or 1, where 0 stands for false and any nonzero value stands for true.

An expression created using a relational operator forms what is known as a relational expression or a condition. Relational operators can be seen as special cases of logical predicates.

Equality

Usage

Equality is being used in many programming-language constructs and data types. It is used to test whether an element already exists in a set, or to access to a value through a key. It is used in Switch statements to dispatch the control flow to the correct branch, and during the unification process in logic programming.