1. Invitation to Computer Science 5th Edition
Chapter 10
The Tower of Babel

2. Objectives In this chapter, you will learn about:
The reason for the proliferation of programming languages (Why Babel?)
Procedural languages
Special-purpose languages
Alternative programming paradigms
Invitation to Computer Science, 5th Edition

3. Why Babel? Reasons for the proliferation of programming languages
Proliferation of programming tasks
Different philosophies have developed about how people should think when they are writing programs
Invitation to Computer Science, 5th Edition 3

4. Procedural Languages Procedural language programs
Tell the computer in a step-by-step fashion how to manipulate the contents of memory locations
Invitation to Computer Science, 5th Edition 4

5. Plankalkül Programming language designed by Konrad Zus
Never widely used
Manuscript describing this programming language
Completed in 1945, but not published until 1972
Invitation to Computer Science, 5th Edition

6. FORTRAN Name derives from FORmula TRANslation
First high-level programming language
Designed to support numerical computations
Allows external libraries of well-written, efficient, and thoroughly tested code modules
Invitation to Computer Science, 5th Edition

7. COBOL Name derives from COmmon Business-Oriented Language
Developed in 1959 and 1960
By group headed by Grace Hopper of the U.S. Navy
Designed to serve business needs such as managing inventories and payrolls
Programs use natural language phrases
Invitation to Computer Science, 5th Edition

8. COBOL (continued) COBOL programs
Highly portable across many different COBOL compilers
Quite easy to read
Very well-suited to manipulating large data files
Invitation to Computer Science, 5th Edition

9. C / C++ C Reasons for popularity
Developed in early 1970s by Dennis Ritchie at AT&T Labs
Originally designed for systems programming, in particular for writing the operating system UNIX
Reasons for popularity
Close relationship between C and UNIX
Efficiency
Invitation to Computer Science, 5th Edition

10. Figure 10.1 User Hardware Interface and Programming Languages
Invitation to Computer Science, 5th Edition

11. Figure 10.2 C Allows Access to a Memory
Cell Address as well as to its Content
Invitation to Computer Science, 5th Edition

12. C / C++ (continued) C includes a data type called pointer
Variables of pointer type
Contain memory addresses
Device driver
Program that interacts with an I/O device
C is the most widely used language for writing system software
Invitation to Computer Science, 5th Edition

13. C / C++ (continued)
C++
Developed in the early 1980s by Bjarne Stroustrup, at AT&T Labs
Provides ability to do object-oriented programming
Commercially released by AT&T in 1985
Invitation to Computer Science, 5th Edition

14. Figure 10.3 Storing a Value in a Specific Memory Location Using C
Invitation to Computer Science, 5th Edition

15. Ada
Named after Ada Augusta Byron Lovelace, daughter of the poet Lord Byron and wife of Lord Lovelace
Current Ada 2005 standard
Amended version of the Ada 95 standard
Accepted in:
The defense industry
Other technological applications
As a general-purpose language
Invitation to Computer Science, 5th Edition

16. Java Applications Applets Bytecode
Standalone programs that reside and run on a self-contained computer
Applets
Programs designed to run from Web pages
Embedded in Web pages on central servers
Bytecode
Can be easily translated into any specific machine language
Invitation to Computer Science, 5th Edition

17. Python
Originally created in the early 1990s by Guido van Rossum at Stichting Mathematisch Centrum
An interpreted language
Originally used for system administration tasks and as a Web interface language
Invitation to Computer Science, 5th Edition

18. C# and .NET Garbage collection Microsoft .NET Framework
Reclaiming memory no longer needed by the program
Microsoft .NET Framework
Essentially a giant collection of tools for software development
Handles garbage collection for a C# program
All .NET programs are compiled into Microsoft Intermediate Language (MSIL) code
Invitation to Computer Science, 5th Edition

19. C# and .NET (continued)
Difference between the Java approach and the .NET approach
Java bytecode translator is an interpreter
More than 40 programming languages:
Have been adapted to fit into the .NET Framework
April 2003
C# and the CLI were adopted as ISO standards
Invitation to Computer Science, 5th Edition

20. Special-Purpose Languages
SQL (Structured Query Language)
Designed to be used with databases
Language used to frame database queries
Developed by IBM
Adopted by ANSI, in 1986, as the standard query language in the United States
Databases
Collections of related facts and information
Can be queried
Invitation to Computer Science, 5th Edition

21. HTML HTML document HTML tags
Consists of the text to be displayed on the Web page, together with a number of special characters called tags
HTML tags
Enclosed in angle brackets (< >) and often come in pairs
Invitation to Computer Science, 5th Edition

22. Figure 10.4 HTML Code for a Web Page
Invitation to Computer Science, 5th Edition

23. Figure 10.5 Body of the Web Page Generated by Figure 10.4
Invitation to Computer Science, 5th Edition

24. Figure 10.6 Some HTML Tags
Invitation to Computer Science, 5th Edition

25. JavaScript Scripting language HTTP POST message
“Lightweight” language that is interpreted
HTTP POST message
Indicates that data is to be passed to the server
JavaScript function ValidateName()
Placed within <script></script> tags to alert the browser that these statements are to be interpreted as JavaScript commands
Invitation to Computer Science, 5th Edition

26. Figure 10.7 An Example of the HTML <form> Tag
Invitation to Computer Science, 5th Edition

27. Figure 10.8 JavaScript Embedded in an HTML Page
Invitation to Computer Science, 5th Edition

28. Alternative Programming Paradigms
Model or mental framework for representing or thinking about something
Alternative paradigms for programming languages include viewing a program’s actions as:
A combination of various transformations on items
A series of logical deductions from known facts
Multiple copies of the same subtask
Invitation to Computer Science, 5th Edition

29. Functional Programming
Functional programming language
Views every task in terms of functions
In a functional programming language:
Primitive functions are defined as part of the language
Functions
Once defined, can be used in the definition of other functions
Invitation to Computer Science, 5th Edition

30. Functional Programming (continued)
list function
Creates a list out of arguments
car function
Takes a nonempty list as its argument and produces as a result the first element in that list
cdr function
Takes a nonempty list as its argument and produces as a result the list that remains after the first element has been removed
Invitation to Computer Science, 5th Edition

31. Functional Programming (continued)
null?
Has a single list as its argument
Evaluates to true if the list is nil (empty) and to false if the list is nonempty
Recursive
Something that is defined in terms of “smaller versions” of itself
Side effect
Occurs when a function changes other values that it has no business changing
Invitation to Computer Science, 5th Edition

32. Figure 10.9 Scheme Program to Add Nonnegative Integers
Invitation to Computer Science, 5th Edition

33. Logic Programming In logic programming: Logic programming Fact
Various facts are asserted to be true, and on the basis of these facts, a logic program can infer or deduce other facts
Logic programming
Has been used to write expert systems
Fact
Expresses a property about a single object or a relationship among several objects
Invitation to Computer Science, 5th Edition

34. Logic Programming (continued)
Prolog rule
Declaration of an “if A then B” form, which means that if A is true (A is a fact), then B is also true (B is a fact)
Inference engine
Piece of software that is supplied as part of the language itself
Invitation to Computer Science, 5th Edition

35. Figure 10.10 A Prolog Program
Invitation to Computer Science, 5th Edition

36. Figure 10.11 The Logic Programming Paradigm
Invitation to Computer Science, 5th Edition

37. Parallel Programming Parallel processing SIMD MIMD
Catchall term for a variety of approaches to computing architectures and algorithm design
SIMD
Single control unit broadcasts a single program instruction to multiple ALUs
MIMD
Interconnected processors independently execute their own program on their own data
Invitation to Computer Science, 5th Edition

38. Figure 10.12 “Grand Challenge” Computing Problems
Invitation to Computer Science, 5th Edition

39. Figure 10.13(a) Model of SIMD Processing
Invitation to Computer Science, 5th Edition

40. Figure 10.13(b) Model of MIMD Processing
Invitation to Computer Science, 5th Edition

41. Parallel Programming (continued)
Message passing primitives
SEND/RECEIVE commands used to exchange information
Divide-and-conquer model
Problem is successively partitioned into smaller and smaller parts and sent off to other processors until each one has only a trivial job to perform
Invitation to Computer Science, 5th Edition

42. Figure 10.14 A Divide-and-Conquer Approach Using Multiple Processors
Invitation to Computer Science, 5th Edition

43. Summary Each programming language was designed to meet specific needs
Procedural programming language: FORTRAN
Object-oriented languages: Ada, Java, C++, C#
Special-purpose languages: SQL, HTML, JavaScript
A functional programming language views every task in terms of functions
Invitation to Computer Science, 5th Edition

44. Summary (continued)
Logic programming: various facts are asserted to be true, based on whether the program infers or deduces other facts
Parallel programming
SIMD (single instruction stream/multiple data stream)
MIMD (multiple instruction stream/multiple data stream)
Invitation to Computer Science, 5th Edition