C #include

• ✅ #include <filename>
• ✅ #include "filename"

The #include directive instructs the compiler to search for the location where system header files are stored. In UNIX systems, this is typically the \usr\include directory.

The #include "filename" directive instructs the compiler to search in the present working directory for the specified file.

#include directive example

Let's explore a basic illustration of the #include directive. Within this code, we include the stdio.h file to access the printf function, which is declared within that specific file.

Example

#include<stdio.h>

 int main(){  

   printf("Hello C");    

   return 0;

 }

Output:

Hello C

#include notes:

Note 1: Comments are not acknowledged within the #include directive. Therefore, when using #include <a//b>, the text a//b is interpreted as the filename.

In the #include directive, the backslash is interpreted as regular text rather than an escape sequence. Therefore, when using #include <a\nb>, "a\nb" is recognized as part of the filename.

Note 3: It is important to remember that you are only allowed to include comments after the filename, as any other content will result in an error.