C++ Include Directive Explained

In C++, the include directive is used to include the content of other files in the current file. Its purpose is to insert the content of the included file at the location of the directive during compilation, so that the functions, variables, or other entities defined in the included file can be used in the program.

Using the include directive allows you to include header files (.h files) in your source files, so that you can utilize the functions, classes, constants, and other definitions from the header files in your source code. Typically, header files contain function prototypes, class definitions, and constant declarations.

For example, if there is a header file named “example.h” that contains function declarations:

// example.h
void myFunction();

By including the header file in another source file using the include directive, you can use the function in the source file.

// main.cpp
#include "example.h"

int main() {
    myFunction();
    return 0;
}

By using the include directive, external code can be modularized and reused where necessary to improve code readability and maintainability.