CISC 110 Day 2

1. CISC 110Day 2 Programming Basics

2. Outline • Comments • Data Types • Conditional Statements (Branching) • Loops • Functions • Variable Scope

3. Comments Two Ways to Comment Code: // This is a comment /* This is a comment spanning multiple lines */ 3

4. Data Types Integer (e.g. 5) Number (e.g. 5.5) String (e.g. “Hello!”) Boolean (true/false) 4

5. Operators: == (is equal to) != (not equal to) > (greater than) >= (greater than or equal to) < (less than) <= (less than or equal to) Comparison Operations

6. Boolean Data Type Example: var x:Boolean; x = (1 == 1); trace(x); Output: true 6

7. Conditional Statements Statements: if (…something is true…) { …execute these lines of code… } else { …else, execute these lines of code… } 7

8. Conditional Statements Example: var x = 10; if(x <= 100) { trace(“Howdy!”); } Output: Howdy! 8

9. Conditional Statements Example: var x = 100; if(x <= 10) { trace(“Howdy!”);} else { trace(“Heya”);} Output: Heya 9

10. Logical Operators Operators: && (and) e.g. (true && true) == true (true && false) == false || (or) e.g. (true || false) == true 10

11. Logical Operators Example: var x = 1; var y = 2; if((x == 1) && (y == 2)) { trace(“Howdy!”); } Output: Howdy! 11

12. While Loop Statement: while (…something is true…) { …execute these lines of code… }

13. While Loop Example: var x = 1; while(x < 10) { x += 1; } trace(x); Output: 10 13

14. For Loop Statement: for(…until condition is not true…) { …execute these lines of code… } 14

15. For Loop Example: for(var k = 1; k < 10; k = k + 1) { trace(“!”); } Output: ! ! ! ! ! ! ! ! ! 15

16. For Loop Example: for(var k = 1; k < 10; k++) { trace(“!”); } Output: ! ! ! ! ! ! ! ! ! 16

17. Functions Example: function displayMessage() { trace(“I\’m in a function!”); } displayMessage(); Output: I’m in a function! 17

18. Function with Argument Example: function displayMessage(message:String) { trace(message); } displayMessage(“I\’m in a function!”); Output: I’m in a function! 18

19. Function with Arguments Example: function displayMessage(m1:String, m2:String) { trace(m1+m2); } displayMessage(“Well…”,” Hello…”); Output: Well…Hello… 19

20. Function with Return Value Example: var s:String = “”; function createMessage(x:String):String { return “Hello “ + x + ”!”; } s = createMessage(“CISC 110”); trace(s); Output: Hello CISC 110! 20

21. Variable Scope Scope means where variables exist, and can therefore be accessed, in a program. Local Variables: Variables defined inside a function only exist within that function. They are created when the function starts executing and are destroyed when it finishes. Global Variables: Variables defined outside of a function exist everywhere after they’re defined, except inside a function with a duplicate variable name. 21

22. Variable Scope Example: var s:String = “”; function createMessage(x:String) { return “Hello “ + x + ”!”; } s = createMessage(“CISC 110”); trace(x); Output: undefined 22

23. Null null:A variable can be assigned to the value “null” (e.g. var x = null;). undefined:Variables should not be assigned to the value “undefined” – this is the value automatically assigned to variables that have not been assigned to any other value. 23