This is my humble opinion about different sections within the code script.
At first place, before main function, we have Preprocessor Directive. It starts with hashtag # and than continues with header file within <>, ends without semicolon. It include code that’s already written in that header file and ready to use in our code.
Then we have main function which consists of expression, declaration and return statements that end with semicolon.
Declaration statements introduce new variables in our code.
Expression statements are all other statements that are not Declaration and Return statements.
Return statement return a value that indicate to Operating System were there an error or not during execution of code. Zero returned means there weren’t any errors and ± one means there were. 