How to use operator () of C++

This article mainly introduces "how to use C++ 's operator ()". In daily operation, I believe many people have doubts about how to use C++ 's operator (). The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts about "how to use C++ 's operator ()". Next, please follow the editor to study!

The overloading operator is sometimes required in the C++ language: (), today we will mainly introduce its main applications.

Parody function

Consider a simple example: suppose you have a vector, and your task is to count the number of string whose length is less than 5. If you use the count_if function, your code may look like this:

Bool LengthIsLessThanFive (const string& str) {

Return str.length () < 5

}

Int res = std::count_if (vec.begin (), vec.end (), LengthIsLessThanFive)

The third argument to the count_if function is a function pointer that returns a value of type bool. In general, if you need to pass in a specific threshold length, we might write the function as follows:

Bool LenthIsLessThan (const string& str, int len) {

Return str.length ()