# How do you pass a functor to a function in C++?

## How do you pass a functor to a function in C++?

You cannot pass a functor as a function pointer into a function that takes a function pointer, even if the functor has the same arguments and return value as the function pointer. Similarly, if a function expects a functor, you cannot pass in a function pointer.

## Can templates be used for functions?

Templates are powerful features of C++ which allows us to write generic programs. We can create a single function to work with different data types by using a template.

**Is functor a function?**

Functors are functions with a state.

**What is the difference between a functor and a function pointer?**

While either a functor or function would work, functors are actually more efficient since calling them does not require any indirection. The compiler can statically determine from the functor type which overloaded operator is called, while calling through a function pointer generally requires a dereference at runtime.

### Why do we need functor in C++?

Functors: Function Objects in C++ Both C and C++ support function pointers, which provide a way to pass around instructions on how to perform an operation. But function pointers are limited because functions must be fully specified at compile time.

### What is the need of templates in C++?

Templates are very useful when implementing generic constructs like vectors, stacks, lists, queues which can be used with any arbitrary type. C++ templates provide a way to re-use source code as opposed to inheritance and composition which provide a way to re-use object code.

**What is a functor vs function?**

A function assigns to every element of a set X an element of a set Y. A functor assigns to every object of a category C an object of a category D and also assigns to every morphism in C a morphism in D in a way compatible with sources, targets, and composition.

**Why do we use functor in C++?**

## Is a functor a function pointer?

Functors. Functors, or function objects, are similar to function pointers, and can be used in similar ways. A functor is an object of a class type that implements the function-call operator, allowing the object to be used within expressions using the same syntax as a function call.