`std::bind`

can be used for function composition, which is the process of combining multiple functions to create a new function. By binding the result of one function as an argument to another function, you can create a composite function that performs a sequence ofÂ operations.

Consider the followingÂ example:

```
#include <functional>
#include <iostream>
int Multiply(int a, int b) { return a * b; }
int Add(int a, int b) { return a + b; }
int main() {
auto MultiplyBy2 = std::bind(
Multiply, 2, std::placeholders::_1);
auto AddMultiplyBy2 = std::bind(
Add, std::placeholders::_1,
std::bind(MultiplyBy2, std::placeholders::_1)
);
// 5 + (5 * 2)
std::cout << AddMultiplyBy2(5) << '\n';
// 10 + (10 * 2)
std::cout << AddMultiplyBy2(10) << '\n';
}
```

```
15
30
```

In this example, we have two simple functions: ** Multiply** and

`Add`

We first create a functor ** MultiplyBy2** by binding the first argument of

`Multiply`

`2`

Next, we create another functor ** AddMultiplyBy2** by binding the second argument of

`Add`

`MultiplyBy2`

`Add`

The resulting ** AddMultiplyBy2** functor takes a single argument, multiplies it by 2 using

`MultiplyBy2`

When we call ** AddMultiplyBy2(5)**, it effectively computes

`5 + (5 * 2)`

`15`

`AddMultiplyBy2(10)`

`10 + (10 * 2)`

`30`

Function composition using ** std::bind** allows you to create new functions by combining existing functions in a declarative way. It can be particularly useful when working with higher-order functions and creating reusable functionÂ components.

Here's another example that demonstrates function composition with multiple boundÂ functions:

```
#include <cmath>
#include <functional>
#include <iostream>
int main() {
auto Square = std::bind(
std::multiplies<int>(),
std::placeholders::_1,
std::placeholders::_1
);
auto SquareRoot = std::bind(
static_cast<double (*)(double)>(std::sqrt),
std::placeholders::_1
);
auto SquareRootOfSquare = std::bind(
SquareRoot,
std::bind(Square, std::placeholders::_1));
// sqrt(5 * 5)
std::cout << SquareRootOfSquare(5) << '\n';
// sqrt(10 * 10)
std::cout << SquareRootOfSquare(10) << '\n';
}
```

```
5
10
```

In this example, we create two functors: ** Square** and

`SquareRoot`

`Square`

`std::multiplies`

`SquareRoot`

`std::sqrt`

We then compose these functors to create a new functor ** SquareRootOfSquare**, which takes a single argument, squares it using

`Square`

`SquareRoot`

When we call ** SquareRootOfSquare(5)**, it effectively computes the square root of

`5`

`5`

`SquareRootOfSquare(10)`

`10`

`10`

Function composition using ** std::bind** allows you to create complex operations by combining simpler functions, promoting code reuse andÂ expressiveness.

Answers to questions are automatically generated and may not have been reviewed.

This Question is from the Lesson:### Function Binding and Partial Application

This lesson covers function binding and partial application using `std::bind()`

, `std::bind_front()`

, `std::bind_back()`

and `std::placeholders`

.