1. Introduction to languages

2. Computer languages
• Source of communication
• To communicate with the computer user
needs to have a language that should be
understood by the computer

3. Two categories
• Low level language
• High level language

4. Low level language
• Machine language
• Lowest and most elementary level language
• Only language which computer can understood
string of binary digits(0’s &1’s)
• 0’s-absences of electrical pulse
• 1’s-presences of electrical pulse

5. Merits & demerits
MERITS
• Fast and Efficient
• No translator needed
DEMETRITS
• All operation codes &memory addresses have
to be remembered
• It is hard to find error
• Machine dependent –particular machine
language cane be used on only one type of
computer

6. Assembly languages
• Operation codes and operands are given in
the form of alphanumeric symbols instead of
0’s & 1’s
• Mnemonics codes and can have maximum up
to 5 letters(SUB,START,LABEL etc..,)
• Symbolic programming language

7. Merits & Demerits
MERITS
• Easier to understand and use
• Easy to locate and correct errors
• Easy to modify
DEMERITS
• Machine dependent
• Programmer should have the knowledge of
the hardware also

8. High level language
• Close to English language
• Enable to write programs easily
• Symbolic language that use English words and
mathematical symbols
• Many language have been developed for
achieving different variety of tasks

9. languages
• BASIC : Beginners All Purpose Symbolic
Instruction Code
• FORTRAN : Formula Translation
• PL/1 : Programming Language version 1
• ALGOL : Algorithm Language
• APL : A Programming Language
• COBOL : Common Business Oriented
Language
• RPG : Report Program Generator
• LISP : List Processing
• PROLOG : Program In Language

10. Merits
• User friendly and easier to learn enquire less time
to write
• Easier to maintain
• Problem oriented rather than machine based
• Program written in high level language can be
translated into many machine language and
therefore can run on any computer for which
there exists an appropriate translator compiler
and interpreter

11. Interpreter
• Converts one level of language to another
language

12. Compiler and interpreter
compiler
• Converts the high level
instructions into machine
• Entire program is executed
• List of errors is created by
the compiler after the
compilation process
• An independent executable
file is created
interpreter
• Convert high level
instruction into intermittent
form
• After translating the first
line an interpreter then
executes it
• Stop translating after the
first error
• Required an interpreter
program each time

13. C Features
• MODULARITY
• PORTABILITY
• EXTENDABILITY
• SPEED
• FLEXIBILITY

14. HISTORY OF C
• Fortran compiler
• Ken Thompson
• New high level language B for developing a
compiler
• Based on BCPL (Basic Combined Programming
Language) developed by Martin Richard

15. C
• AT’s & T’s Bell Lab (USA) in 1972
• Dennis Ritchie
• Purpose : to design the Unix -os
• PL/1,ALGOL,etc
• The ANSI formed a committee in 1983
• This committee approved a version of c in
1989 which is known as ANSIC
• ANSI C was then approved by the
international standard organization (ISO) in
1990