BASIC STRUCTURE OF C PROGRAMS

1. EVERY PROGRAM EXECUTION STARTS WITH THE MAIN FUNCTION .
2. ALL THE STATEMENTS ARE TERMINATED WITH A SEMICOLON ( ; ) .
3. INSTRUCTIONS ARE CASE - SENSITIVE .
4. INSTRUCTIONS ARE EXECUTED IN THE SAME ORDER IN WHICH THEY ARE WRITTEN.

COMMENT -------> ARE USED TO CLARIFY SOMETHING  ABOUT THE PROGRAM . IT IS A WAY FOR US TO ADD NOTES TO OUR PROGRAM .

THERE ARE 2 TYPES OF COMMENTS IN C LANGUAGE .

1. SINGLE LINE COMMENT = / /  ( THIS IS A COMMENT ) .
2. MULTI - LINE COMMENT = IN STARTING  ( / * ) AND END ME ( * / ) .

• COMMENTS IN A C PROGRAM ARE NOT EXECUTED AND ARE IGNORED . 

 There are six main sections to a basic c program.

The six sections are,

1. Documentation
2. Link
3. Definition
4. Global Declarations
5. Main functions
6. Subprograms

Documentation Section

The documentation section is the part of the program where the programmer gives the details associated with the program. He usually gives the name of the program, the details of the author and other details like the time of coding and description. It gives anyone reading the code the overview of the code.

Example

/**

* File Name: Helloworld.c

* Author: Manthan Naik

* date: 09/08/2019

* description: a program to display hello world

Link Section

This part of the code is used to declare all the header files that will be used in the program. This leads to the compiler being told to link the header files to the system libraries.

Example

#include<stdio.h>

Definition Section

In this section, we define different constants. The keyword define is used in this part.

Example

#define PI=3.14

Global Declaration Section

This part of the code is the part where the global variables are declared. All the global variable used are declared in this part. The user-defined functions are also declared in this part of the code.

Example

float area (float r);

fint a=7;




Main Function Section

Every C-programs needs to have the main function. Each main function contains 2 parts. A declaration part and an Execution part. The declaration part is the part where all the variables are declared. The execution part begins with the curly brackets and ends with the curly close bracket. Both the declaration and execution part are inside the curly braces.

Example

int main(void)

{

int a= 10;

printf(" %d", a);

return 0;

}




Sub Program Section

All the user-defined functions are defined in this section of the program.

Example

int add(int a, int b)

{

return a+b;

}