C++ #include Directive Explained

In C++, the include directive is used to include header files. Header files typically contain class declarations, function prototypes, and other declarations needed in the source code.

The syntax of the include directive is as follows:

#include <header_file>

Here, header_file refers to the name of the header file that needs to be included. The header file can be from the C++ standard library or custom user-defined header files.

The include directive will insert the contents of the specified header file into the current source file, allowing the code in the source file to use the classes, functions, etc. declared in the header file.

Typically, the naming convention for header files is to use .h or .hpp as the suffix. For example, iostream is a header file in the C++ standard library, and we can include it in the following way:

#include <iostream>

After including the header file, you can use the classes and functions related to input and output defined in the iostream in the source file.