There are following structures of a basic C program.
- Documentation Section
Documentation section consists of a sets of comment lines including name of the program, name of the author and other details.
This section uses comments.
It is written after // if comment is in one line only. Otherwise the section is written inside /* */ if the comment line is in one or more lines.
- Linker Section
Linker Section provides instruction to the compiler to link functions with program from the system library.
It links header files to the program.
It starts with #include and include header files having .h extensions.
For example:
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
- Definition Section
In this section we can define symbolic constants and macros.
It is also known as macros definition.
It begins with #define
- Global Variable Section
This section is used to declare global variables and function prototypes.
Global variables are that variables which are used in more than one functions.
A function prototype is a declaration of the function that tells the program about the type of the value returned by the function and the number and type of arguments.
- Main() Function Section
The main() function is mandatory in C programming.
This part of programming contains the statements that are to be executed by the compiler.
C program can’t run without a main function.
It has two parts
1) Declaration part
2) executable parts
- Subprogram Section
This section consists of all the user defined functions which are called in main function
It is optional section. i.e. C program can run without a subprogram. But it is used to simplify the program and to reduce the effort.