Generations of Programming Languages

1. Generations of Programming Languages • First generation • Machine Language • Second Generation • Assembly Language • Third Generation • Procedural language such as Pascal, C, Basic etc. • Fourth Generation • Non-procedural language, more natural.

2. Machine language • 10110000 01100001

3. Assembly Language • mov al, 061h

4. Popular Programming Languages • FORTRAN—the oldest high-level programming language; designed for scientific and mathematical applications.

5. Popular Programming Languages, Cont’d. • COBOL—designed for business transaction processing.

6. Popular Programming Languages, Cont’d. • Pascal—designed to teach structured programming; useful for math and science applications.

7. Popular Programming Languages, Cont’d. • BASIC—an easy-to-learn beginner’s programming language. • Visual Basic—an object-oriented, third-generation version of BASIC.

8. Popular Programming Languages, Cont’d. • C, C++, C#—versions of the highly efficient C programming language; C++ and C# are object-oriented.

9. Popular Programming Languages, Cont’d. • Java—object-oriented programming language commonly used for Web applications. • Platform independence—Java programs can run on any platform that supports the Java Virtual Machine.

11. Popular Programming Languages, Cont’d. • Other high-level languages: • Ada • APL • LISP • Logo • PL/1 • Prolog • RPG • SmallTalk

12. SQL – 4GL Select address from Patients Where Patients.name = “Johnson” And Patients.age < 65

13. JavaScript HIMA 4160

14. What is JavaScript • Programming language designed for webpage • To increase interactivity and dynamics • Applications • Form validation • Shopping cart • Calculations • Special graphic and text effects • Online email systems (Yahoo, Hotmail) • Online mapping (Google Map) • Online productivity suite (Google doc, ZOHO)

15. Before talking about JavaScript, we need to talk about form in HTML

16. HTML Form Explanation: http://www.w3schools.com/html/html_forms.asp

17. JavaScript Syntax • Unlike HTML, JavaScript is case sensitive. • Dot Syntax is used to combine terms. • e.g., document.write("Hello World") • Certain characters and terms are reserved. • JavaScript is simple text (ASCII).

18. JavaScript Terminology • JavaScript programming uses specialized terminology. • Understanding JavaScript terms is fundamental to understanding the script. • Objects, Properties, Methods, Events, Functions, Values, Variables, Expressions, Operators.

19. Objects • Objects refers to windows, documents, images, tables, forms, buttons or links, etc. • Objects should be named. • Objects have properties that act as modifiers.

20. Properties • Properties are object attributes. • Object properties are defined by using the object's name, a period, and the property name. • e.g., background color is expressed by: document.bgcolor . • documentis the object. • bgcoloris the property.

21. Methods • Methods are actions applied to particular objects. Methods are what objects can do. • e.g., document.write(”Hello World") • document is the object. • write is the method.

22. Events • Events associate an object with an action. • e.g., the onMouseover event handler action can change an image. • e.g., the onSubmit event handler sends a form. • User actions trigger events.

23. Functions • Functions are named statements that performs tasks. • e.g., function doWhatever () {statement here} • The curly braces contain the statements of the function. • JavaScript has built-in functions, and you can write your own.

24. Values • Values are bits of information. • Values types and some examples include: • Number: 1, 2, 3, etc. • String: characters enclosed in quotes. • Boolean: true or false. • Object: image, form • Function: validate, doWhatever

25. Variables • Variables contain values and use the equal sign to specify their value. • Variables are created by declaration using the var command with or without an initial value state. • e.g. var month; • e.g. var month = “April”;

26. Expressions • Expressions are commands that assign values to variables. • Expressions always use an assignment operator, such as the equals sign. • e.g., var month = “May”; is an expression. • Expressions end with a semicolon.

27. Operators • Operators are used to handle variables. • Types of operators with examples: • Arithmetic operators, such as plus. • Comparisons operators, such as equals. • Logical operators, such as and. • Control operators, such as if. • Assignment and String operators.

28. JavaScript Syntax: Dynamic Typing • Idea • No need to declare variable type • A value is only checked from proper type when it is operated upon • Example var x = 5; //int x = 5.5; //float x = “five point five” //String y=x/2 //wrong

29. Methods of Using JavaScript. 1. JavaScripts can reside in a separate page. 2. JavaScript can be embedded in HTML documents -- in the <head>, in the <body>, or in both. 3. JavaScript object attributes can be placed in HTML element tags. e.g., <body onLoad="alert('WELCOME')">

30. 1. Using Separate JavaScript Files. • Linking can be advantageous if many pages use the same script. • Use the source element to link to the script file. <script src="myjavascript.js” language="JavaScript1.2” type="text/javascript"> </script>

31. 2. Embedding JavaScript in HTML. • When specifying a script only the tags <script>and </script>are essential, but complete specification is recommended: <script language="javascript” type="text/javascript"> <!-- Begin hiding window.location=”index.html" // End hiding script--> </script>

32. Using Comment Tags • HTML comment tags should bracket any script. • The <!-- script here -->tags hide scripts in HTML and prevent scripts from displaying in browsers that do not interpret JavaScript. • Double slashes //are the signal characters for a JavaScript single-line comment.

33. 3. Using JavaScript in HTML Tags. • Event handlers like onMouseover are a perfect example of an easy to add tag script. <a href=”index.html” onMouseover="document.logo.src='js2.gif'" onMouseout="document.logo.src='js.gif'"> <img src="js.gif" name="logo"> </a>

34. Creating an Alert Message • The following script in the <body>tag uses the onLoad event to display an Alert window • The message is specified within parenthesis. <body onLoad="alert('WELCOME. Enjoy your visit. Your feedback can improve cyberspace. Please let me know if you detect any problems. Thank you.')">

35. Generating HTML Dynamically • Idea • Script is interpreted as page is loaded, and uses document.write or document.writeln to insert HTML at the location the script occurs • Template … <body> Regular HTML <script type=“text/javascript”> <!-- Build HTML Here // --> </script> More regular HTML </body>

36. A Simple Script <html> <head> <title>First JavaScript Page</title> <head> <body> <h1>First Javascript Page</h1> <script type=“text/javascript”> <!-- document.write(“<hr>”); document.write(“Hello World Wide Web”); document.write(“<hr>”); //--> </script> </body> <html>

37. Simple Script, Result

38. Monitoring User Events • Use various onXxx attributes related to HTML tags • onClick • onLoad • onMouseOver • onFocus • …

39. User Events, Example <html> <head> <title>Simple JavaScript Button</title> <script type=“text/javascript”> <!-- function dontClick(){alert(“I told you not to click!”); } //--> </script> </head> <body bgcolor=“white”> <h1>Simple JavaScript Button</h1> <form> <input type=“button” value = “Don’t click Me” onClick=“dontClick()”> </form> </body> </html>

40. User Events, Result

41. JavaScript Syntax: Function Declaration • Declaration syntax • Functions are declared using the function reserved word • The return value is not declared, nor are the types of the arguments • Example: function square(x){ return(x*x); } function factorial(n){ if (n <= 0){ return(1); } else{ return (n * factorial(n-1)); } }

42. Next Class • Bring your laptop on Thursday.