1. Lecture 8 Programming Paradigm & Languages

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!

28. THANK YOU