C programming Language and Data Structure

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C programming Language and Data Structure
For DIT Students
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Course Detail
Theory 100 Piratical 100 Total 200
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Introduction to C Programming

• Introduction

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Books

• Turbo C Programming for PC, Robert Lafore, SAMS
• Data Structure ,Schaums Series

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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

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Program

• Set of instructions which perform any specific
  task is called program.

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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.

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History of C language
Year Language Developer
1960 ALGOL (Algorithmic Language) Internal Committee
1967 BCPL (Basic Combined Programming Language) Martin Richards
1970 B Ken Thompson
1972 C Dennis Ritchie
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What is C?

• C
• A language written by Dennis Ritchie in 1972 at
  ATT 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. ATT-American
Telephone and Telegraph UNIX-Uniplexed
Information and Computing System or Service
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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

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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

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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.

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Sample Pseudo code

• Task add two numbers
• Pseudo code (Algorithm)
• Start
• Get two numbers
• Add them (a b)
• Print the answer
• End

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What does a flowchart look like?

• Pseudo code (Algorithm)
• Start
• Get two numbers
• Add them (A B)
• Print the answer
• End

Start
Get 2 numbers
AB
Print answer
End
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Flow Chart symbols

• START/END
• INPUT/OUTPUT
• PROCESS
• DECISION

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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.

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Simple C Program

• / A first C Program/
• include ltstdio.hgt
• void main()
•      printf("Hello World")

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Simple C Program

• / A first C Program/
• include ltstdio.hgt
• void main()
•      printf("Hello World")

Header File
Preprocessor directive
Main Function
Opening bracket
Statement Part
Closing Bracket
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Simple C Program

• Line 1 include ltstdio.hgt
• 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.

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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.

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Simple C Program

• Line 3
• This opening bracket denotes the start of the
  program.

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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.

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Simple C Program

• Line 5
• This closing bracket denotes the end of the
  program.

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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/

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Getting started with C

• Steps in learning English language
• Steps in learning C

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The C character Set

• A character denotes any alphabet, digit or
  special symbol used to represent information.

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Constants, Variable and keywords

• The alphabets, numbers and special symbol when
  properly combined form constants, variables and
  keywords
• A constant is a quantity that doesnt 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

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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 double if static do break else int stru
ct goto case enum long switch signed char ex
tern near typedef while const float register u
nion default continue far return unsigned for s
hort void
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Escape Sequence

• Certain non printing characters can be expressed
  in terms of escape sequences
• \n new line
• \t tab
• \a alert
• \\ backslash
• \ double quote
• \0 Null
• \b Backspace

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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 Description
Typical Memory int
integer quantity 2
bytes char single
character 1 bytes float
floating point number 4 bytes

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Escape Sequences in C

• Certain non printing characters can be expressed
  in terms of escape sequences

Character Escape Sequence
bell \a

backspace \b horizontal
tab \t
vertical tab \v newline
\n
carriage return \r
quotation mark () \ question
mark(?) \? backslash (\)
\\ null
\0
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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 -gt 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.

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Program Development
Editor
Source File
Preprocessor
Modified Source Code in RAM
Compiler

Program Object Code File
Linker
Executable File
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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