Documentation :This section consists of the description of the program, the name of the program, and the creation date and time of the program.

It is specified at the start of the program in the form of comments.

Documentation can be represented as:

// description, name of the program, programmer name, date, time etc.
or

/*
description, name of the program, programmer name, date, time etc.
*/

Anything written as comments will be treated as documentation of the program and this will not interfere with the given code.

Preprocessor Section :

• All the header files of the program will be declared in the preprocessor section of the program.
• Header files help us to access other’s improved code into our code.
• A copy of these multiple files is inserted into our program before the process of compilation.

Example :

Definition :

• Preprocessors are the programs that process our source code before the process of compilation.
• There are multiple steps which are involved in the writing and execution of the program.
• Preprocessor directives start with the '#' symbol.
• The #define preprocessor is used to create a constant throughout the program
• Whenever this name is encountered by the compiler, it is replaced by the actual piece of defined code.
Example:

#define long long ll

Global Declaration :

• The global declaration section contains global variables, function declaration, and static variables.
• Variables and functions which are declared in this scope can be used anywhere in the program.
Example:

int num = 18;

Main() Function :

• Every C program must have a main function.
• The main() function of the program is written in this section.
• Operations like declaration and execution are performed inside the curly braces of the main program.
• The return type of the main() function can be int as well as void too.
• void() main tells the compiler that the program will not return any value.
• The int main() tells the compiler that the program will return an integer value.
Example:

void main()
or
int main()

Sub Programs :

• User-defined functions are called in this section of the program.
• The control of the program is shifted to the called function whenever they are called from the main or outside the main() function.
• These are specified as per the requirements of the programmer.
Example:

int sum(int x, int y)
{
return x+y;
}