Lec 11 Programming Languages new upload.pptx

Programming languages intro

1. PROGRAMMING LANGUAGES Lecture # 11

2. 2 The major part of computing is software. To develop software, programming languages are used. To understand the role of programming languages in computing. To understand the differences among low- & high-level , interpreted & compiled , and structured & object-oriented programming languages . LEARNING GOALS FOR TODAY

3. 3 Programming ?

4. 4 The process of telling the computer what to do Also known as coding

5. 5 Types of Programs ?

6. TYPES OF PROGRAMS Batch Program Event-Driven Program

7. 7 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

8. EXAMPLE? Suppose you are working in a company , hundreds of people are working in that company, at the end of the month you have to pay salaries . You just give one command to computer i.e. prepare the pay roll . No further interaction with computer . The program automatically fetch the data and print the check or send advice to bank. In the whole process when it started till its end. User have no interaction with program.

9. 9 EVENT-DRIVEN PROGRAMS Examples? GUIs, microwave, camera Event driven program interact with user while the program is running, sometimes instead of user they interact with sub-parts that generates events in computer. The system sends events to the program and the program responds to these as they arrive. 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

10. 10 Programming Language ?

11. 11 A vocabulary and set of grammatical rules for instructing a computer to perform specific tasks

12. 12 ALL PROGRAMS CONSISTS OF: Sequence of instructions Conditionals Loops These may contain: Data (Text etc) Input/output (print, etc) Operations (add, divide, etc)

13. 13 Examples of Programming Language ?

14. Machine Language Assembly Language (1956-63) LISP (1956) Fortran (1957) COBOL (1959) PL/1 (1964) BASIC (1964) Pascal (1970) Smalltalk (1972) C (1972) Ada (1983) C++ (1983-85) QBasic (1986) Perl (1987) VisualBasic (1991) PowerBuilder Java (1995) JavaScript C# (2001)

15. 15 Is HTML a programming language ?

16. CLASSIFICATION OF PROGRAMMING LANGUAGES Business Languages: COBOL having report writing capabilities. Scientific Languages: FORTRAN and ALGOL Educational Languages: PASCAL & LOGO use when teaching the principles of programming.

17. System Programming: C has been developed to write operating systems and associated system programs. Object Oriented Programming: C++, DELPHI, SMALLTALK and EIFFEL. Artificial Intelligence: PROLOG has been developed to implement these applications.

18. WHAT DOES PROGRAMMING LOOK LIKE ? Here are some examples of an instruction to print the word HELLO in different programming language. Logo PR [ HELLO] JavaScript alert(“ HELLO”); FORTRAN PRINT “ HELLO” BASIC PRINT “ HELLO” COBOL DISPLAY ‘ HELLO’. C printf (“HELLO”) C++ cout <<“HELLO”; Pascal WRITELN(‘ HELLO’); Assembly XPRNT MESSAGE1 Language MESSAGE1 DC ‘ HELLO’

19. 19 Types of Programming Languages ?

20. CLASSIFICATION OF PROGRAMMING LANGUAGES

21. 21 High level Programming Languages Low Level Programming Languages

22. 22 High-level programming languages , while simple compared to human languages, are more complex than the languages the uP actually understands , called machine languages Each different type of microprocessors has its own unique machine language

23. 23 Lying between machine languages & high-level languages are languages called assembly languages

24. 24 Assembly languages are similar to machine languages, but are easier to program in as they allow a programmer to substitute names for numbers An assembly language instruction has a mnemonic to describe the operation and allows the programmer to name memory location. The assembly language instruction is converted into the machine code instruction by an assembler program . Machine languages consist of numbers only

25. A SAMPLE ASSEMBLY LANGUAGE PROGRAM A sample assembly language program for adding two numbers and storing the result . START PROGRAM AT 0000 START DATA AT 1000 SET ASIDE AN ADDRESS FOR FRST SET ASIDE AN ADDRESS FOR SCND SET ASIDE AN ADDRESS FOR ANSR CLA FRST ADD SCND STA ANSR HLT

26. Assembler Assembly code Object code

27. 27 4th-generation languages High-level languages Assembly languages Machine languages

28. PowerBuilder is 4 th generation language. More complex task can performed with one statement.

29. 29 Regardless of what language you use , you eventually need to convert your program into a language that the computer can understand Two ways for doing that: compile the program or interpret the program

30. 30 Interpreter is a program that executes instructions written in a high-level language An interpreter translates high-level instructions line by line into an intermediate form, which it then executes In contrast , a C ompiler translates high-level instructions directly into machine language

31. 31 Compiled programs generally run faster than interpreted programs The advantage of an interpreter, however, is that it does not need to go through the compilation stage during which the whole of the high-level code is translated into machine instructions in one go . This process can be time-consuming if the program is long. The interpreter can immediately execute high-level programs, without waiting for the completion of the translation process

32. 32 Interpreters: Immediate response, but execute code slowly Compilers: Takes longer to compile, but super-fast execution

33. 33 Both interpreters and compilers are available for most high-level languages. However, BASIC and LISP were especially designed to be executed by an interpreter

34. CLASSIFICATION OF PROGRAMMING LANGUAGES

35. 35 Procedural Languages Non-Procedural Languages

36. PROCEDURAL LANGUAGES In procedural languages and programs used to tell the computer exactly what to do , step by step . In other words, what to do and how to do is required. Example: Fortran, Cobol, C++ etc…

37. NON-PROCEDURAL LANGUAGES In non-procedural languages and programs is where you tell computer , and it figures out how to get it . Non-procedural languages is often used for database manipulation . Example: Query Languages i.e. SQL

38. 38 Why are there so many different programming languages ?

39. 39 What is the difference between them ?

40. 40

41. 41 What are the advantages of particular languages ?

42. 42

43. 43 The question of which language is best is one that consumes a lot of time and energy among computer professionals Every language has its strengths and weaknesses

44. 44 FORTRAN is a particularly good language for processing numerical data, but it does not lend itself very well to large business programs Pascal is very good for writing well-structured and readable programs, but it is not as flexible as the C programming language C++ embodies powerful object-oriented features, but it is complex and difficult to learn

45. 45 The choice of which language to use can also depend on the: type of computer the program is to run on, and the expertise of the programmer

46. FORTRAN FORTAN stands for FOR mula TRAN slation . Developed by John Backus and his team at IBM . FORTAN language is oriented towards solving problem of a mathematical nature . It has been designed as algebra-based programming language . FORTAN 90 is the latest version of FORTRAN standardized by ANSI .

47. A SAMPLE FORTRAN PROGRAM A sample FORTRAN language program for compute and print the sum of 10 numbers . C FORTRAN PROGRAM TO COMPUTE C THE SUM OF 10 NUMBERS SUM = 0 DO 50 I = 1, 10 READ (5, 10) N SUM = SUM + N 50 CONTINUE WRITE (6, 20) SUM 10 FORMAT (F6.2) 20 FORMAT (1X, ‘THE SUM OF GIVEN NUMBERS = ’, F10.2) STOP END

48. COBOL COBOL stands for CO mmon B usiness O riented L anguage. Developed by Grace Hoper and his team . It was developed for business data processing language . Business data processing application deal with corporate accounting information , automate inventory control , billing and payroll .

49. It has English -like commands . COBOL 2002 is the latest version of COBOL standardized by ANSI .

50. 50 A Sample COBOL program (1) IDENTIFICATION DIVISION PROGRAM_ID SUMUP. AUTHOR. P K SINHA. * THIS PROGRAM COMPUTES AND PRINTS * THE SUM OF GIVEN NUMBERS. ENVIRONMENT DIVISION. CONFIGURATION SECTION. SOURCE_COMPUTER BURROUGHS_6700. OBJECT_COMPUTER BURROUGHS_6700. INPUT_OUTPUT SECTION. FILE_CONTROL. SELECT DATA_FILE ASSIGN TO DISK. SELECT OUTPUT_FILE ASSIGN TO PRINTER. To be Continue on next slide

51. 51 A Sample COBOL program (2) DATA DIVISION. FILE SECTION. FD DATA_FILE RECORD CONTAINS 80 CHARACTERS LABEL RECORD IS OMITTED DATA RECORD IS INPUT_DATA_RECORD. 01 INPUT_DATA_RECORD. 05 N PICTURE 9(6)V99. 05 FILLER PICTURE X(72). FD OUTPUT_FILE RECORD CONTAINS 132 CHARACTERS LABEL RECORD IS OMITTED DATA RECORD IS OUTPUT_RECORD. To be Continue on next slide

52. 52 A Sample COBOL program (3) 01 OUTPUT_RECORD. 05 FILLER PICTURE X. 05 TITLE PICTURE X(25). 05 SUM PICTURE 9(10)V99. 05 FILLER PICTURE X(94). WORKING_STORAGE SECTION 77 MESSAGE PICTURE X(25) VALUES IS “THE SUM OF GIVEN NO.” PROCEDURE DIVISION. OPEN_FILES. OPEN INPUT DATA_FILE OPEN OUTPUT OUTPUT_FILE To be Continue on next slide

53. 53 A Sample COBOL program (4) INITIALIZATION. MOVE SPACES TO OUTPUT_RECORD MOVE ZERO TO SUM. PROCESS_LOOP. READ DATA_FILE AT END GO TO PRINT_PARA. ADD N TO SUM. GO TO PROCESS_LOOP. PRINT_PARA. MOVE MESSAGE TO TITLE. WRITE OUTPUT_RECORD. END_OF_JOB. CLOSE DATA_FILE. CLOSE OUTPUT_FILE. STOP RUN.

54. BASIC BASIC stands for B eginners A ll-purpose S ymbolic I nstruction C ode. Developed by Prof . John Kemeny & Thomas Kurtz at Darmouth College in USA. It was developed to use for both business & scientific applications . Users of BASIC range from school students to scientists & engineers to business managers .

55. It was designed to use an interpreter as the language translator (FORTRAN & COBOL use compilers). BASIC has many dialects including BASICA, QBSIC and Visual Basic .

56. 56 A Sample BASIC program A sample BASIC program . 5 REM PROGRAM TO COMPUTE 6 REM THE SUM OF 10 NUMBERS 10 LET S = 0 20 FOR I = 1 TO 10 30 READ N 40 LET S = S + N 50 NEXT I 60 PRINT “THE SUM OF GIVEN NUMBERS = ”; S 70 DATA 4, 20, 15, 32, 48 80 DATA 12, 3, 9, 14, 44 90 END;

57. PASCAL Named after, French mathematician, Blaise Pascal. Developed by Prof. Nicklaus Wirth of Federal Institute of Technology in Zurich, Switzerland. It was develop for beginners to learn good problem solving and programming practices . PASCAL was based on the concepts associated with structured programming an object oriented version of Pascal is also available.

58. Hence, it is recognized as an educational language , used to teach programming to beginners . PASCAL is suitable for both scientific and business applications .

59. 59 A Sample PASCAL program PROGRAM SUMNUMS (INPUT, OUTPUT); (* PROGRAM TO COMPUTE THE SUM OF 10 NUMBERS *) (* DECLARATION OF VARIABLES*) VAR SUM, N : REAL; VAR I : INTEGER; (* MAIN PROGRAM LOGIC STARTS HERE*) BEGIN SUM := 0; FOR I := 1 TO 10 DO BEGIN READ (N); SUM := SUM + N; END; WRITELN (‘THE SUM OF GIVEN NUMBERS=’, SUM); END;

60. DATA TYPES In a high-level language a constant or a variable represents one or more memory locations where data can be stored.

61. SIMPLE DATA TYPES Most languages offer some primitive data types such as: Integer: to store whole numbers. Real: to store values that contain digits after the decimal point. Character: to store a single character. Boolean: to store one of the two values, True or False.

62. COMPLEX DATA TYPES It is possible to use more complex data types : Array: a collection of items, each of which can be accessed directly using a subscript, e.g. Table[5] refers to the fifth item in the array. String: naturally an array of characters but sometimes offered as a special type.

63. 63 Array An indexed list of elements We said that a variable is a container that holds a value. Similarly, an Array can be considered a container as well, but this one can hold multiple values

64. 64 Array An indexed list of elements Example: There are many ways of assigning identifiers to the following fruit strawberry fruit1 fruit[ 0 ] orange fruit2 fruit[ 1 ] apple fruit3 fruit[ 2 ] watermelon fruit4 fruit[ 3 ]

65. 65 Array An indexed list of elements fruit[ 0 ], fruit[ 1 ], fruit[ 2 ], and fruit[ 3 ] are the elements of an array ‘fruit’ is the identifier for that array The length of the ‘fruit’ array is 4, i.e. ‘fruit’ has four elements

66. 66 Array fruit [ ] Identifier Square bracket Index

67. ABSTRACT DATA TYPES Abstract data types (ADTs) are complex data types that have operations associated with them. To access an ADT ask it to perform some operations , e.g. a stack that has the operations Push and Pop . To add an item to the stack you use Push and to remove an item from the stack you would use Pop.

68. Abstract data types include: Queue: a first in first out (FIFO) data structure. Items are retrieved in the same sequence that they were added. Stack: a last in first out (LIFO) data structure. Items are retrieved in the reverse sequence Binary Search Tree: items are added in any sequence . A useful structure that automatically sorts the data.

69. 69 ? Programming SW Development

70. 70 SW Design Methodology ?

71. 71 The set of (often flexible) rules and guidelines a team of developers follow to construct reasonably complex SW systems

72. 72 Object Oriented Design (1) OO SW is all about objects: a black box which receives messages & responds with those of its own An object has 2 aspects : State, also termed as properties, data Example: For the bicycle: color, speed, pressure Behaviors, also termed as methods, instructions Example: For the same object: accelerate(), inflate() In traditional design, these 2 aspects have been kept apart

73. 73 Object Oriented Design (2) The designer starts with any component (object) of the system; designs it as an independent, self-contained system, and then moves to the design of some other component The over-all system is put together by fitting together a collection of these components Key feature: Details of the design of the component are kept independent of the over-all system Benefit: It can be easily re-used in other systems: design once; use multiple times

74. 74 Structured Design (1) Also called top-down design The designer starts by first conceiving a skeleton high-level design of the system, and then starts defining features of that over-all design in an ever-increasing detail Making small changes in the functionality of the systems sometimes leads to major re-design exercise

75. 75 Structured Design (2) Structured design emphasizes separating a program's data from its functionality Separating data from functionality typically leads to SW that is difficult to maintain & understand - especially for large SW systems

76. 76 Object-Oriented Languages Programming languages specifically designed to make it easy to implement object-oriented designs Examples: Smalltalk, C++, Java

77. 77 Reading Material Programming Languages http://www.wikipedia.com/wiki/Programming_language What is Object-Oriented Software? http://catalog.com/softinfo/objects.html VisualBasic : Taming the Wooly Mammoth http://computer.org/software/so2000/pdf/s3016.pdf