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Standard Template Library Programmer's Guide
(document number: 007-3426-004 / published: 1999-05-21) table of contents | additional info | download
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Predicate


Category: functors	Component type: concept

Description

A Predicate is a Unary Function whose result represents the truth or falsehood of some condition. A Predicate might, for example, be a function that takes an argument of type int and returns true if the argument is positive.

Refinement of

Unary Function

Associated types

Result type The type returned when the Predicate is called. The result type must be convertible to bool.

Notation

`F`	A type that is a model of Predicate
`X`	The argument type of `F`
`f`	Object of type `F`
`x`	Object of type `X`

Valid expressions

Name	Expression	Type requirements	Return type
Function call	`f(x)`		Convertible to `bool`

Expression semantics

Name	Expression	Precondition	Semantics	Postcondition
Function call	`f(x)`	`x` is in the domain of `f`.	Returns `true` if the condition is satisfied, `false` if it is not.	The result is either `true` or `false`.

Predicate

Description

Refinement of

Associated types

Notation

Valid expressions

Expression semantics

Complexity guarantees

Invariants

Models

Notes

See also