CIS 365: Visual Application Development Introduction to Computers and Programming

Objectives Computer Operations Programming Languages VB.Net Language Programming Process Modular Structure Procedural Code Algorithms

Computer Operations (inputs/processes/outputs)

Programming Languages 1 st Generation (Machine Languages) Represented instructions as sequence of binary numbers 2 nd Generation (Assembly Languages) Replaced numbers with abbreviated words Required translator programs (assemblers) to convert assembly into machine language Low Level Machine-dependent, only run on certain computers Use instructions tied to specific hardware Many instructions required for a single operation

Programming Languages 3 rd Generation Procedure-oriented, 1 instruction=many operations, focus on problem instead of hardware Object-oriented, use objects with properties, behaviors, reuse of objects is the goal 4 th Generation 4GL: allow users to access/format without writing code Visual-oriented: permit programmer to manipulate graphical objects directly with code to support objects High Level Written using instructions resemble English language Can be translated to run on a variety of computer types

Programming Languages Procedural Decisions about actions and order of actions are controlled by the programmer, not user Event-Driven User controls sequence of events by action taken User chooses between options by selecting an object which triggers an event that runs a specific procedure Still requires procedures to be coded

VB.NET Language It allows event-driven programming It is object-oriented Everything revolves around objects Each object has properties and methods Properties are characteristics Methods are actions the object can take Some objects can raise events, i.e. notify other objects that something happened

The Programming Process 1. Understand the problem: (Analysis) The description of what the user needs; inputs/processes/outputs A good programmer is often part counselor, part detective 2. Plan the logic: (Design) Programmer plans the steps to the program, deciding what steps to include and how to order them. Common tools are flowcharts, pseudocode, and IPO (Input/Processing/Output) Table 3. Code the program (Coding) Translate design of logic into desired language syntax 4. Test the program (Testing) Unit Test, Integrated Test, System Test 5. Put the program into production (Implementation) Load it on user(s) computers and train them

Modular Structure Modular Programs: programs whose structure consists of interrelated forms and tasks, arranged in a logical and easily undertandable order to form an integrated unit Easy to develop, correct, and modify Each module is designed/developed to perform a clearly defined and specific function Visual Basic: Form Modules (code and objects on form) General Procedures: procedural code that performs processing tasks Sub Procedures Function Procedures

Procedural Code Sequence: ordered list of operations Selection: control the flow of operation Iteration: repeat operations until a certain exit condition is met

Algorithms Before programming, must understand: Data to be used Desired result Steps required to produce result Algorithm is a list of steps, step-by-step sequence of instructions How data is to be processed to produce the desired output Not bound to a programming language, the “English” version of the program The algorithm is more important than the language

Summary Computer Operations Input Processing Output

Summary Programming languages come in a variety of forms and types Machine languages Assembly languages Procedural languages Object oriented languages 4GL Visual languages

Summary VB.Net is: Event-driven Object-oriented Graphical

Summary Software Development Process: Analysis Design Algorithms Flow Charts, PseudoCode, IPO Tables Coding Modular Procedural Sequence/Selection/Iteration Testing Implementation