Operator (computer programming)

In computer programming, an operator is a programming language construct that provides functionality that may not be possible to define as a user-defined function (e.g. sizeof in C) or has syntax different from that of a function (e.g. infix addition as in a+b). Like other programming language concepts, operator has a generally accepted, although debatable, meaning among practitioners.

Some operators are represented with symbols – characters typically not allowed for a function identifier – to allow for presentation that is more familiar looking than typical function syntax. For example, a function that tests for greater-than could be named gt, but many languages provide an infix symbolic operator so that code looks more familiar. For example, this:

if gt(x, y) then return

Can be:

if x > y then return

Some languages allow a language-defined operator to be overridden with user-defined behavior and some allow for user-defined operator symbols.

Operators may also differ semantically from functions. For example, short-circuit Boolean operations evaluate later arguments only if earlier ones are not false.