Introduction to C Programming - I

Introduction to
C Programming
V.V.Subrahmanyam,
Sr. Lecturer,
SOCIS, IGNOU
Date: 04-02-07
Time: 12-00 to 12-45

The best way to escape the
problem is to solve it.
Alan
Saporta

Introduction
Knowledge in a programming language
is prerequisite to the study of most of
the computer science courses.
A programming language is the
principal interface with the computer.
Understanding the variety of
programming languages and the design
trade offs between the different
programming paradigms makes it much
easier to master new languages
quickly.

Algorithm: It is a series of steps
arranged in a logical sequence to solve
the problem.
Flowchart: It is a pictorial
representation of a sequence of
instructions using some predefined
symbols.
Algorithm and a Flowchart

Programming Language and
Program
Programming Language: In practice, it is
necessary to express an algorithm using
some programming language to instruct the
computer to solve the problem.
Program: A sequence of instructions written
in any programming language to solve the
problem using a computer.

Categories of Programming
Languages
Low level languages or Machine
oriented languages:
Whose design is governed by the circuitry
and the structure of the machine.
Difficult to learn
These are designed to give a better machine
efficiency i.e., faster program execution.
Machine dependent.
Examples: Machine language, Assembly
language

High level languages or Problem
Oriented languages
These are oriented towards describing
the procedures for solving the problem.
Machine Independent
Easy to learn
Machine directly cannot understand
them.
Examples: FORTRAN, PASCAL, C etc.

C Programming Language
Developed at AT & T Bell Laboratory in
1970’s.
Designed by Dennis Ritchie.

Salient features of C
General Purpose, structured
programming language.
It can considered as a High level
language, however as it combines both
the features, it can be treated as a
Middle level language.
Portable
Easy to debug
Easy to test and maintain

Structure of a C Program
Preprocessor directives
Global data declarations
main()
{
Declaration part;
----
Program Statements;
--
---
---
}
User defined functions

A Simple C Program
/* Program to print a message*/
#include <stdio.h>
main()
{
printf(“I am in the first semester of MCAn”);
}

Program to add to numbers
/* Program to add to numbers*/
#include <stdio.h>
main()
{
int a, b , sum;
printf (“ Enter the values of a and b:n”);
scanf(“%d, %d”, &a, &b);
sum = a+b;
printf(“the sum is %d”, sum);
}

C Character Set
Uppercase Letters: A to Z
Lowercase Letters: a to z
Digits: 0 to 9
Certain Special characters as building
blocks to form basic program elements
(e.g. constants, variables, operators,
expressions etc..)
Special symbols: %, &, +, _ , - # etc.

Identifiers
Identifiers are the names that are given
to the various program elements, such
as variables, functions and arrays.
Identifiers consist of letters and digits, in
any order, except the first character
must be a letter.
Both upper case and lower case are
allowed.

Contd..
No special symbols, except the
underscore(_) is allowed.
An identifier can also begin with an
underscore(_).
Examples: x, y12, sum_1, amount, _temp
etc..

Keywords
Reserved words that have standard,
predefined meaning in C language.
These are used for intended purpose
only, these cannot be used as
programmer-defined identifiers.
Examples: auto, break, case, switch, for,
goto, struct etc..

Basic Data types
Data type Description Typical Memory
Requirements
Int Integer 2 bytes or one
word
Char A character 1 byte
Float Decimal
number
4 bytes
Double Double
precision
8 bytes

Constants
Interger Constants
Floating-point constants
Character Constants
String Constants

Variables
It is an identifier that is used to
represent some specified type of
information within a designated portion
of a program.
Is used to represent a single data item
(a numerical quantity or a character
constant).
The data item must be assigned to the
variable at some point of the program
and later it can be referenced with the
name.

Declarations
A declaration associates a group of
variables with a specific data type..
In C, all the variables must be declared
before they can appear in executable
statements.
Examples: int a;
int a, b, c;
char flag;

Symbolic Constants
It is the name that substitutes for a
sequence of characters.
The characters may represent a
numeric constant, a character constant
and a string constant.
Examples: #define RATE 0.23
#define PI 3.1415
#define TRUE 1

STATEMENTS
A statement causes the computer to
carry out some action.
 Expression statement
 Compound statement
 Control statement

Arithmetic Operators
Operator Purpose
+ Addition
- Subtraction
* Multiplication
/ Division
% Remainder after
the division

Relational Operators
Operator Meaning
< Less than
<= Less than or equal to
> Greater than
>= Greater than or
equal to
== Equal to
!= Not equal to

Logical Operators
Operator Meaning
&& And
|| Or

Assignment Operator
Identifier = expression
Examples: a = 3;
x=y;
area = Length * breadth

Conditional Operator
expr1 ? Expr 2 : expr 3
Example: (i<0) ? 0: 100;
j= (f<g) ? f: g;

Introduction to C Programming - I

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Introduction to C Programming - I