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Preprocessor Directives | Getting Started
C++ Introduction
course content

Course Content

C++ Introduction

C++ Introduction

1. Getting Started
2. Variables and Data Types
3. Introduction to Operators
4. Introduction to Program Flow
5. Introduction to Functions

bookPreprocessor Directives

To add external files to your program you have to use preprocessor directives. These are the commands that guide the preprocessor, a tool that transforms code before compilation. The syntax for most preprocessing directives is:

  • #: symbol that indicates that it is a preprocessing directive;
  • directive: specific preprocessing directive;
  • parameters: the associated value or argument for that directive.

The command that adds external files to your program is called #include.

Note

Standard files are attached using angle brackets < >, but you can also create your own files and connect them to your project similarly, using double quotes " ".

How #include works

Look at the code below and try to run it.

cpp

main

copy
1234
int main() { return 0;

You get an error of a missing }. This is done on purpose to show how the #include works. We can create a separate file containing only the } symbol and include it in the main.cpp file using the #include directive.

cpp

main

h

header

copy
1234
int main() { #include <header.h>

The issue has been resolved, and you should no longer encounter an error. The reason for this resolution lies in the nature of the #include directive, which essentially just copies and pastes the content of a file at the point where it is called.

What is preprocessor directive to add external files?

What is preprocessor directive to add external files?

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Section 1. Chapter 5
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