Course Content
C++ Introduction
C++ Introduction
Preprocessor 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.
main
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.
main
header
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.
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