This document provides an overview of the C and C++ programming languages. It discusses the importance of C, including its robustness, efficiency, portability, and ability to structure programs and extend functionality. The basic structure of a C program is outlined, including documentation, link, definition, global declaration, main function, and sub-program sections. Details are given about what code belongs in each section and examples are provided.

1. PROGRAMMING IN C &
C++
Subject Code : 18UMAA31
Subject In-charge : Mr.S.Viswanathan

2. Importance of C
Popularity of C is due to many qualities,
• Robust Language – Means rich set of built-in functions and operators are
used.
• It is efficient and fast – due to its variety of data types and powerful
operators.
• Example: Incrementing a variable from 0 to 15000 take one second

3. Cont…
• Highly Portable – Means Program written in one computer can be run on
another.
• Suited for Structured Programming – Makes program debugging, testing
and maintenance easier.
• Ability to Extend itself – Means we can add our own functions to make
the program simple.

4. Basic Structure of C Program
DOCUMENTATION SECTION
LINK SECTION
DEFINITION SECTION
GLOBAL DECLARATION SECTION
Continue..

5. Cont…
Main() Function Section
{
}
Declaration Part
Executable Part
Sub Program Section Function 1
Function 2
Function N
.
.
.
.
.
.
(User –
Defined
Functions)

6. Cont…
• Documentation Section – Consists of Comment lines for mention the
followings,
1) Name of the Program
2) Author of the Program
3) Other needed Details (created date, function name details
etc..)

7. Cont…
• Link Section – It gives instructions to compiler to link the built in functions
from system library.
Ex: #include<stdio.h>
#include<conio.h>
• Definition Section – It defines all the symbolic constants.
Ex: #define PI 3.14

8. Cont…
• Global Declaration Section – Variables that are used in more than one functions
are declared in this section.
Ex:
int a = 10; // Global Variable
int add(){ int sub(){
Printf(“%d”,a); Printf(“%d”,a);
} }

9. Cont…
• main() Function Section – Every program must have a main function.
• It consists of two sections,
1) Declaration Part
2) Executable Part
Declaration Part – Declares all the needed variables for a program.
Executable Part – At least one statement should be in the executable part.
• Program execution begins at the opening brace({ ) and ends at the closing brace ( } )

10. Cont…
• Sub-Program Section – Contains all user-defined functions
• User-Defined functions are placed after the main() Section.