Chapter #13 Computer Programs and Programming Languages

Computers Programs and Programming Languages

• A computer program is a series of instructions that directs a computer to perform tasks - Created by a programmer using a programming language.

Low-Level Languages 

• Machine language is the first generation of programming languages.
• Only language the computer directly recognizes.
• Assembly language is the second generation of programming languages.
• Programmer writes instructions using symbolic instruction codes.
• A source program contains the code to be converted to machine language.

Procedural Languages

• In a procedural language, the programmer writes instructions that tell the computer what to accomplish and how to do it - Third-generation language (3GL)

1. A compiler translates an entire program before executing it.
2. An interpreter converts and executes one code statement at a time.

• The C programming language is used to write many of today's programs
• COBOL (Common Business-Oriented Language) is designed for business applications but easy to read because of the English-like statements.

Object-Oriented Programming Languages and Program Development Tools

• An object-oriented programming (OOP) language allows programmers the ability to reuse and modify existing objects.
• Other advantages include :

1. Objects can be reused
2. Programmers create applications faster
3. Work well in a RAD environment
4. Most program development tools are IDEs

• Java is an object-oriented programming language developed by Sun Microsystems.
• The Just-in-time (JIT) compiler converts the bytecode into machine-dependent code.
• The Microsoft .NET Framework allows almost any type of program to run on the Internet or an internal business network, as well as cmputers and mobile devices.
• Features include :

1. CLR (Common Language Runtime)
2. Classes

• C++ is an extension of the C programming language.
• C# is based on C++ and was developed by Microsoft.
• F# combines the benefits of an object-oriented language with those of a functional language.
• Visual Studio is Microsoft's suite of program development tools

1. Visual Basic is based on the BASIC programming language.
2. Visual C++ is based on C++.
3. Visual C# combines the programming elements of C++ with an easier, rapid-development environment.

• A visual programming language is a language that uses a visual or graphical interface for creating all source code.
• Borland's Delphi is a powerful program development tool that is ideal for building large-scale enterprise and Web applications in a RAD environment.
• PowerBuilder is a powerful program development RAD tool.

Other Programming Languages and Development Tools

• Best suited for WEB-based, .NET, and large-scale enterprise object-oriented applications.
• A 4GL (forth-generation language) is a nonprocedural language that enables users and programmers to access data in database - One popular 4GL is SQL.
• Classic programming languages include :

1. Ada
2. ALGOL
3. APL
4. BASIC
5. Forth
6. FORTRAN
7. HyperTALK
8. LISP
9. Logo
10. Modula-2
11. Pascal
12. PILOT
13. PL/1
14. Prolog
15. RPG
16. Smalltalk

• An application generator is a program that creates source code or machine code form a specification of the required functionality. - Often bundled as part of a DBMS
• A macro is a series of statements that instructs an application how to complete a task.
• You usually create the macro in one of two ways :

1. Record the macro with macro recorder
2. Write the macro

Web Page Development

• HTML is a special formatting language that programmers use to format documents for display on the Web.
• XHTML is a markup language that allows Web sites to be displayed more easily on mobile devices.
• XML allows Web developers to create customized tags and use predefined tags to display content appropriately on various devices. - WML is a subset of XML and is used to design pages for micro browsers. 
• Two applications of XML are RSS 2.0 and ATOM.
• Web browsers can execute short programs to add interactive elements to Web pages.
• To send and receive information between your computer and a Web server, these programs use the CGI (common gateway interface)

1. Scripts
2. Applets
3. Servlets
4. ActiveX controls

• Programmers write scripts, applets, servlets, or ActiveX controls using a variety of languages.

1. JavaScript
2. Perl
3. PHP
4. Rexx
5. Tcl
6. VBScript

• Web 2.0 allows Web sites to provide a means for users to :

1. Share personal information
2. Allow users to modify Web site content
3. Have application software built into the site

• Most Web 2.0 sistes use APIs - An API enables programmers to interact with an environment such as a Web site or operating system.
• Web page authoring software can create sophisticated Web pages that include images, video, audio, animation, and other effects.

1. Dreamweaver
2. Expression Web
3. Flash
4. SharePoint Designer

Multimedia Program Development

• Multimedia authoring software allows programmers to combine text, graphics, animation, audio, and video in an interactive presentation.

1. ToolBook
2. Director

Program Development

• Program development consists of a series of steps programmers use to build computer programs.

Step 1 - Analyze Requirements

• To initiate program development, programmer :

1. Reviews the requirements
2. Meets with the systems analyst and users
3. Identifies input, processing, and output

Step 2 - Design Solution

• Design a solution algorithm.
• In structured design, the programmer typically begins with a general design and moves toward a more detailed design.
• Programmers use a hierarchy chart to show program modules graphically.
• With object-oriented (OO) design, the programmer packages the data and the program into a single object.
• The sequence control structure shows one or more actions following each other on order.
• The selection control structure tells the program which action to take, based on a certain condition.

1. If-then-else
2. Case

• The repetition control structure enables a program to perform one or more actions repeatedly as long as a certain condition is met.
• A program flowchart graphically shows the logic in a solution algorithm.
• Flowcharting software makes it easy to modify and update flowcharts.

1. SmartDraw
2. Visio 

• Pseudocode uses a condensed form of English to convey program logic.
• UML (Unified Modeling Language) has been adopted as a standard notation for object modeling and development.

Step 3 - Validate Design

• Check for logic errors using test data

1. Develop various sets of test data
2. Determine the expected result
3. Step through the algorithm
4. Compare the results
5. Repeat steps for each set of test data

Step 4 - Implement Design

• Implementation of the design includes using a program development tool that assists the programmer by :

1. Generating or providing some or all code.
2. Writing the code that translates the design into a computer program.
3. Creating the user interface.

• Extreme programming is a strategy where programmers immediately begin coding and testing solutions as soon as requirements are defined.

Step 5 - Test Solution

• The goal of program testing is to ensure the program runs correctly and is error free.

1. Errors include syntax errors and logic errors.
2. Debugging the program involves removing the bugs.
3. A beta is a program that has most or all of its features and functionality implemented.

Step 6 - Document Solution

• In documenting the solution, the programmer performs two activities :

1. Review the program code
2. Review all the documentation