Developing Applications

1
Developing Applications

• Notes for Chapter 14
• Digital Domain, 2 ed

2
Programming Languages

• Programs consist of sequence of instructions
  performed within the fetchexecute cycle
• All instructions must be in a particular
  processors machine language before that
  processor can execute them
• machine languages are expressed in binary codes
• assembly languages are symbolic versions of
  machine languages
• Higher level languages allow programmers to
  express a process in a more abstract form (closer
  to the actual problem domain)
• these high-level languages must be translated
  into machine languages
• both compiler and interpreter software can be
  used to accomplish this translation

3
Programming Languages (contd)

• Programs often employ variables and functions to
  accomplish their tasks
• Conditional statements alter the flow of control
  within the program sequence
• allow the program to make decision
• move to different sequences of instructions based
  on Boolean conditions (conditions that can be
  true or false)

4
Scripting Languages

• Scripting languages are interpreted languages
• Very useful for Web-related programming tasks
• add interactivity to Web pages
• enable interaction with backend databases

5
The Software Development Cycle

• Analyze and understand the problem
• Devise a plan to solve the problem
• Create an executable program that implements the
  plan
• Test and correct the program

6
Program Plans as Algorithms

• Program plans are expressed as algorithms
• what information is needed?
• what events are needed to process the
  information?
• how must these events be sequenced?
• Algorithms may be expressed using
• flow charts
• pseudocoding
• Translating an algorithm to an executable program
  is called coding

7
Testing and Software Complexity

• Testing involves running a program with the goal
  of finding any errors (sometimes called bugs) so
  they can be corrected
• Large programs are very complex
• testing can rarely uncover all bugs
• beta testing allows program users to help uncover
  additional errors after initial testing is
  completed
• Testing is part of a larger process known as
  software quality assurance

8
Software Development is a Team Effort

• Systems analysts planning and design
• Project manager oversee the schedule and budget
• Programmers work in teams to complete the
  coding
• Quality assurance testing

9
Programming Paradigms

• A programming paradigm defines the basic model by
  which a language expresses a process
• imperative procedural paradigm
• uses modules called procedures or functions
• examples Pascal, BASIC, FORTRAN, COBOL, C, and
  ADA
• object-oriented paradigm
• objects encapsulate both data and process
• objects have attributes (data)
• objects have associated methods (process)
• most scripting languages use this paradigm
• examples Java, C, JavaScript, VBScript, and
  Visual Basic

10
Programming Paradigms (contd)

• nonprocedural paradigm
• often used in artificial intelligence (AI)
  applications
• examples Prolog, LISP, and FP

11
Other Programming Languages

• End-user languages
• Languages for Internet applications
• scripting languages
• event-driven programming
• Languages for extending and integrating
  applications
• visual programming (Visual BASIC)
• AppleScript
• Languages for specialized applications
• Director/Lingo
• Flash/ActionScript

12
Summary

• Programs consist of sequence of instructions
  performed within the fetchexecute cycle
• All instructions must be in a particular
  processors machine language before that
  processor can execute them
• Higher level languages allow programmers to
  express a process in a more abstract form (closer
  to the actual problem domain)
• The software development cycle consists of
• Analyze and understand the problem
• Devise a plan to solve the problem
• Create an executable program that implements the
  plan
• Test and correct the program

13
Summary (contd)

• Software development is a team effort
• Systems analysts planning and design
• Project manager oversee the schedule and budget
• Programmers work in teams to complete the
  coding
• Quality assurance testing
• There are number of programming paradigms
• imperative procedural paradigm
• object-oriented paradigm
• nonprocedural paradigm