For Programming Paradigm & Languages

1. Lecture 8
Programming Paradigm
& Languages
Lecturer: Sumaira Hussain
S.M.I UNiversity

2. Programming Languages
The process of telling the computer what to do
Also known as coding

3. Batch Programs
These are typically started from a shell (or automatically
via a scheduler) and tend to follow a pattern of:
–Initialize internal data
–Read input data
–Process that data
–Print or store results
Key feature: No user interaction with the computer
while the program is running
Examples?
PC are a printing request or an analysis of a Web site log.

4. Event-Driven Programs
Examples? GUIs, microwave, camera
The system sends events to the program and the
program responds to these as they arrive.

5. Event-Driven Programs
Events can include things a user does -like
clicking the mouse -or things that the system
itself does -like updating the clock.
These programs generally work as follows:
–Initialize the internal data
–Wait for events to arrive
–Identify an incoming event and react
accordingly

6. Programming Languages
• Machine Language Assembly Language (1956-63)
• LISP (1956)
• Fortran (1957)
• COBOL (1959)
• PL/1(1964)BASIC (1964)
• Pascal (1970)
• Smalltalk (1972)
• C (1972)

7. Programming Languages
• Ada(1983)
• C++ (1983-85)
• QBasic (1986)
• Perl (1987)
• VisualBasic (1991)
• PowerBuilderJava (1995)
• JavaScriptC# (2001)

8. Programming Language
A language used to write instructions for the
computer. That is the way of representation any
program in to that form which is understandable
by CPU.

9. Programming Language
Programs are written by using any language and
these languages set the procedures & rules to
write computer programs. Programmers have to
follow that rules which is set by programming
languages. Types of Languages
1)Low Level Language
2)High Level Language

10. LOW LEVEL LANGUAGE
Low level language is also called machine
language. That types of languages are close to
machine and easily understand by machine as, it
is majorly in binary form (0 & 1). low level
language types are
Machine language
Assembly language

11. HIGH LEVEL LANGUAGE
High level programming languages is languages
program than use languages or syntax which
closes to human languages so; it is easy to
understanding the languages. This type of
language is machine-independent, and uses
similar language as English, which is easily
understandable by human.

12. TYPES OF HIGH LEVEL LANGUGES
Types of high level languages are:
1) Procedural Languages
2) Functional & Non procedural Languages
3) Object Oriented Languages

13. Procedural programming languages
FORTRAN (FORmula TRANslation)
BASIC (Beginners All Purpose Symbolic
Instruction Code)
COBOL (Common Business Oriented Language)
These types of languages are “Third-
Generation Language”.

14. NON PROCEDURAL LANGUGES
In non-procedural languages the computer is
not limited to a set of precise instructions.
Instead, the programmer defines only the
problem—not the instructions--to solve the
problem. Non Procedural Programming
Languages are
SQL (Structured Query Language)
LISP (List Processing)
PROLOG (PROgramming with LOGic)

15. Object-Oriented Languages
Programming languages specifically designed to
make it easy to implement object-oriented designs
In object-oriented languages, the code used to
write the program and the data processed by the
program are grouped together into units called
objects. Objects are further grouped into classes,
which define the attributes objects must have.
Examples: Smalltalk, C++, Java

16. Language Translator
A translator is a computer program that
translates a program written in a
given programming language into a functionally
equivalent program in a different computer
language, without losing the functional or
logical structure of the original code

17. Types of Language Translator
• Compiler
• Interpreter
• Assembler

18. COMPILER
A compiler is a computer program that
transforms human readable complete code of
another computer program into the machine
readable code that a CPU can execute.

19. INTERPRETER
An interpreter is a computer program that reads
the source code of another computer program
and executes that program. Because it is
interpreted line by line, it is a much slower way
of running a program than one that has been
compiled but is easier for learners because the
program can be stopped, modified and rerun
without time-consuming compiles.

20. ASSEMBLER
Assembler converts code written in assembly
language into machine language. It works same
like interpreter and compiler. The assembler
program takes each program statement in the
code and generates a corresponding bit stream
or pattern (a series of 0's and 1's of a given
length).

21. • Both interpreters and compilers are available
for most high-level languages. However, BASIC
and LISP were especially designed to be
executed by an interpreter

22. FORTRAN
Fortran is a particularly good language for
processing numerical data, but it does not lend
itself very well to large business programs
Pascal
Pascal is very good for writing well-structured and
readable programs, but it is not as flexible as the C
programming language
C++
C++ embodies powerful object-oriented features,
but it is complex and difficult to learn

23. Testing & Debugging
•Testing:
The tasks performed to determine the existence of
defects
•Debugging:
The tasks performed to detect the exact location of
defects
•Defects are also called bugs or errors
•Let us now look at one of their classifications

24. Types of Errors
•Syntax errors
•Semantic errors
•Run-time errors

25. Syntax Errors
•They are caused by the code that somehow
violates the rules of the language
•Easy to detect and fix errors
•The browser stops code interpretation on
detecting one of these
•Examples:
a = b + * c ;
receiver = receiver + 2
Syntax error?

26. Semantic Errors
•Occur when a statement executes and has an
effect not intended by the programmer
•Hard to detect during normal testing
•Often times occur only in unusual & infrequent
circumstances
•The „+‟ operator often results in unintended
consequences. Remedy: Convert, before use

27. Run-Time Errors
•Occur when the program is running and tries to
do something that is against the rules
•Example: Accessing a non-existent variable,
property, method, object, etc (e.g. a method
name is misspelled)
•Sources of these can be determined by a
careful reading of the code, but unfortunately,
not always!