VB NOTES - EG. Java, C++, Visual Basic Focus on objects...

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1/20 ---Programming languages 1. Machine Language The only language computer can recognize e.g. 1000101111100 2. Assembly language e.g. LOAD R2 ADD R3 JUMP 6F 3. High-Level Languages e.g. x=y+3 [ C, Fortran(for engineer), Pascal, COBOL(for business) ] 1 and 2 are different for every computer while 3 could work for all computers 2 and 3 must be translated to machine language before they can be executed ---compiler: a program that do the translation e.g. Fortran program----compiler----machine language program (exe.) ---BASIC: Beginner’s All-purpose Symbolic Instruction Code All these languages are procedural and designed as a set of instructions-focus on actions (verbs) ---Alternative: object-oriented languages (could avoid problems for big programs)
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Unformatted text preview: EG. Java, C++, Visual Basic Focus on objects (nouns) which represent real-world entities Eg. Paychecks, employees, button, label are objects ---Objects have • Properties (attributes) [Name, position for employee, etc.] • Methods (actions) [start, stop, calculate pay, etc.]---Class: an object type Template or blueprint for object. eg. [car, my 2002 status] Why is this good idea? 1. Information hiding (don’t have to know details of implementation) 2. Code re-use (don’t need to write again for existing object like button)---Another VB characteristic • Event-driven • Wait for users input—take some action in response--event handler is a kind of method (action)...
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This note was uploaded on 12/01/2011 for the course 6K 226 taught by Professor Staff during the Fall '10 term at University of Iowa.

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