Chapter 17.7, Problem 17.47CP

Program Plan Intro

Function objects:

An object which is created for a class which overloads the function call operator is function object.

• It resembles like a function and it can be passed as parameter to other functions.
• It is also known as “functor”.
• It can accept arguments and return values.
• Function object can be created, when the class overloads the “parenthesis()” operator which is referred as “function call operator”.

Five basic functor concepts in STL are listed below:

• Generator
• Unary functions
• Binary function
• Unary predicate
• Binary predicate

Predicate:

A function object which returns “boolean” value is termed as “predicate”. It is used with algorithm and takes input data which further proceeds with the course of action.

Some examples of predicate are listed below:

• all_of(), none_of(), any_of()
• equal()
• find_if()