functors in c++

Functors in C++ are objects that act like functions. They're implemented using operator overloading, specifically the operator() function. Here are the steps to create and use a functor:

1. Create a Functor Class: Define a class with operator() overloaded. This will be the function-call operator.

   cpp class MyFunctor { public: void operator()(int x) { // Define functionality here // This is where the functor acts like a function std::cout << "Functor called with value: " << x << std::endl; } };

2. Instantiate the Functor: Create an object of the functor class.

   cpp MyFunctor myFunc;

3. Use the Functor: Call the object like a function using operator(). This executes the code defined in the operator() function.

   cpp myFunc(10); // This will call the operator() function in MyFunctor

4. Passing Functors as Arguments: Functors can be passed as arguments to functions.

   ```cpp void doSomething(MyFunctor func) { func(5); }

   // Usage doSomething(myFunc); // Calls the doSomething function with myFunc as argument ```

5. Lambda Functions as Functors: C++ also supports lambda functions which can act as functors.

   ```cpp auto myLambda = { std::cout << "Lambda called with value: " << x << std::endl; };

   myLambda(7); // Calls the lambda function as a functor ```

Functors provide a flexible way to encapsulate functionality, especially when passing functions as arguments or when using them within algorithms that accept function objects.