#include is also a processor directive.
stdio.h is a header file that contain functions like printf(), scanf() etc.These functions are defined in stdio.h file.So if we don't write #include<stdio.h> , printf() and scanf() functions doesn't work.
I understand what you mean, but pedantically speaking it is a little different.
1. "#include" is [only] a preprocessor directive. The word "also" was misleading.
2. stdio.h is a header file, but it does NOT contain functions like printf(), scanf() etc. Instead, the header file contains macro definitions, typedefs, external variable declarations, and function prototype declarations that are needed in order for a user file to call functions like printf(), scanf(), etc. It contains function
declarations, not function
definitions.