Why used #include <string>?

feedback
1

Why do we use #include in the given problem, there is no use of that library on that place?

2

By using this you can use string data type in you code. Include actually have several operations. So include is a directive and after that you can several functions related to string such as String.size() and etc

3

#include <stdioo.h> is a header file.

is a sub or pre processor .the preprocessor to include the contents of a specified file at the point where the directive appears like library,string …etc that can be included in a header file