C programming Language
and
Data Structure
For DIT Students
Course Detail
Theory
100
Piratical
100
Total
200
Introduction to C
Programming
Introduction
Books

“Turbo C Programming for PC”, Robert Lafore,
SAMS

“Data Structure” ,Schaum’s Series
Language?

Source of Communication between two
persons.
– Example: Human –To- Human

OR
Source of Communication between User
and Computer is called programming
language.
– Example: Human –To- Machine
Program
Set of instructions which perform any
specific task is called program.
What is programming?

Series of instructions to a computer to achieve a task

Instructions must be written in a way the computer can
understand

Programming languages are used to write programs

Once the code (language) of a program has been
written, it must be executed (run, started).

Some programming languages (like C, C++ or Java)
require the code to be compiled (translated to binary)
before it can be started.
History of C language
Year
Language
Developer
1960
ALGOL
(Algorithmic Language)
1967
BCPL
Martin Richards
(Basic Combined Programming Language)
1970
B
Ken Thompson
1972
C
Dennis Ritchie
Internal Committee
What is C?

C

A language written by Dennis
Ritchie in 1972 at AT&T Bell Labs
USA. This was to be the language
that UNIX was written in to become
the first "portable" language.
In recent years C has been used as a general-purpose
language because of its popularity with
programmers.
AT&T-American Telephone and Telegraph
UNIX-Uniplexed Information and Computing System or Service
Why C Still Useful?

C provides:




Efficiency, high performance and high quality
Provide functionality through rich set of function libraries
Gateway for other professional languages like C  C++  Java
C is used:




System software, Compilers, Editors
Graphics and Geometry
Databases, operating systems, device drivers
Also used in application programs
Software Development Method

Requirement Specification
– Problem Definition

Analysis
– Refine, Generalize the problem definition

Design
– Develop Algorithm: (A formula or set of steps for solving a
particular problem)

Implementation
– Write Code

Verification and Testing
– Test and Debug the code
How do you write a program?

Decide what steps are needed to complete the task

Write the steps (Algorithm) in pseudo code (written in English)
or as a flowchart (graphic symbols)

Translate into the programming language

Try out the program and “debug”.
Sample Pseudo code


Task: add two numbers
Pseudo code (Algorithm) :
1.
2.
3.
4.
5.
Start
Get two numbers
Add them (a + b)
Print the answer
End
What does a flowchart look like?

Pseudo code
(Algorithm) :
1. Start
2. Get two numbers
3. Add them (A + B)
4. Print the answer
5. End
Start
Get 2 numbers
A+B
Print answer
End
Flow Chart symbols

START/END

INPUT/OUTPUT

PROCESS

DECISION
Integrated Development Environments

An integrated development environment (IDE) is a software
package that makes it possible to edit, compile, link, execute,
and debug a program without leaving the environment.
16
Simple C Program
/* A first C Program*/
#include <stdio.h>
void main()
{
printf("Hello World");
}
Simple C Program
/* A first C Program*/
#include <stdio.h>
Header File
Preprocessor directive
void main()
{
Opening bracket
printf("Hello World");
}
Main Function
Statement Part
Closing Bracket
Simple C Program

Line 1: #include <stdio.h>

As part of compilation, the C compiler runs a program
called the C preprocessor. The preprocessor is able to
add and remove code from your source file.
In this case, the directive #include tells the
preprocessor to include code from the file stdio.h.
This file contains declarations for functions that the
program needs to use. A declaration for the printf
function is in this file.


Simple C Program

Line 2: void main()

This statement declares the main function.
A C program can contain many functions but must
always have one main function.
A function is a self-contained module of code that can
finish some task.
The "void" specifies the return type of main. In this case,
nothing is returned to the operating system.



Simple C Program

Line 3: {

This opening bracket denotes the start of the program.
Simple C Program

Line 4: printf("Hello World ");

Printf is a function from a standard C library that is used
to print strings to the standard output, normally your
screen.
The compiler links code from these standard libraries to
the code you have written to produce the final
executable.
If there were another printf in this program, its string
would print on the next line.


Simple C Program


Line 5: }
This closing bracket denotes the end of the program.
Comment




Comment should be enclosed between /* */
It is used to increase the readability of the program.
Any number of comments can be given at any place
in the program.
Comment cannot be nested
example:
/* A first C Program*/
Getting started with C

Steps in learning English language
Alphabets

Words
Sentences
Paragraph
Steps in learning C
Alphabets
Digits
Special-symbols
Constants
Variables
Keywords
Instruction
Program
The C character Set
• A character denotes any alphabet, digit
or special symbol used to represent
information.
Alphabets
A,B, …. ,Y, Z
a,b, ….. ,y, z
Digits
0,1,2,3,4,5,6,7,8,9
Special Symbols
~‘!@#%^&*( )_-+=
|\{}[] :;“‘< > , .? /
Constants, Variable and keywords

The alphabets, numbers and special symbol
when properly combined form constants,
variables and keywords

A constant is a quantity that doesn’t change

A variable is a name given to the location in
memory where the constant is stored

Example: 3x + y = 20
3 & 20 are constants, which cannot change
x & y can vary or change hence are called variables
Keywords
• Keywords are the words whose meaning has
already been explained to the C compiler
• Sometimes called reserved words.
• They cannot be used as variable names.
• There are only 32 keywords available in c
auto
break
case
char
const
continue
short
double
else
enum
extern
float
far
void
if
int
long
near
register
return
static
struct
switch
typedef
union
unsigned
do
goto
signed
while
default
for
Escape Sequence
Certain non printing characters can be expressed in terms
of escape sequences







\n
\t
\a
\\
\”
\0
\b
new line
tab
alert
backslash
double quote
Null
Backspace
Data Types
• C Supports several different types of
data, each of which may be represented
differently within the computers memory.
• Basic data types are listed below:
Data Type
int
char
float
Description
integer quantity
single character
floating point number
Typical Memory
2 bytes
1 bytes
4 bytes
Escape Sequences in C

Certain non printing characters can be expressed in terms of
escape sequences
Character
Escape Sequence
bell
backspace
horizontal tab
vertical tab
newline
carriage return
quotation mark (“)
question mark(?)
backslash (\)
null
\a
\b
\t
\v
\n
\r
\”
\?
\\
\0
Development with C

Four stages
 Editing: Writing the source code by using some IDE or editor
 Preprocessing or libraries: Already available routines
 compiling: translates or converts source to object code for a
specific platform
source code -> object code
– linking: The object code of a program is linked with libraries
that are needed for execution of a program. The linker is used to
link the program with libraries. It creates a file
with '*.exe' extension.
Program Development
Editor
Source File
Preprocessor
Modified Source Code in RAM
Compiler
Program Object Code File
Linker
Executable File
Keywords

Sometimes called reserved words.

Are defined as a part of the C language.

Can not be used for anything else!

32 keywords in C

Examples:
– Int
– void
– while
– for