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CISC 110 Day 5. Arrays and Random Numbers. Outline. Data Structures Lists: One-dimensional arrays Array Declarations and Statements Initializing Arrays Size of Arrays length attribute Adding and Removing Elements Random Numbers. Data Structures. - PowerPoint PPT Presentation
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CISC 110Day 5
Arrays and Random Numbers
2
Outline
• Data Structures• Lists: One-dimensional arrays• Array Declarations and Statements• Initializing Arrays• Size of Arrays
– length attribute• Adding and Removing Elements• Random Numbers
3
Data Structures
Data Structures are ways to organize groups ofdata elements.
We have worked with individual variables and withproperties of objects.
4
Data Structures
Examples of Single Variables
4 “Daniel” true38.5
age name height cute
5
Data Structures
A String is actually an object
“Daniel”
6 characters
lengthname
6
Common Ways to Structure Data
1. List (in ActionScript: one-dimensional arrays)
Example Lists: * Shopping List * Marks List * List of Student Names
Physical Structure:
7
Common Ways to Structure Data
2. Table (in ActionScript: 2-dimensional arrays)
Example Tables: * Periodic Table of Elements* Representation of a Chess Board
Physical Structure:
8
Common Ways to Structure Data
3. Record (in ActionScript: objects)
Example Records:
* Student Record
(will have name, address, phone, …)
* MovieClip Record
(will have length, width, rotation, alpha, …)
No Particular Physical Structure
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Common Ways to Structure Data
4. Tree ( in A.S.: objects + references to objects)
Example Trees :
* Company Management Hierarchy
* Family Tree
Physical Structure:
10
Lists: One-dimensional Arrays
A list is a sequence of items, in which each item has a position (i.e., an index)
“Daniel”
“Aislinn”
“Zhixing”
“Anna”
“Ya-Hui”
“Praveena”
“Sumeira”
“Meghan”
0
1
2
3
4
5
6
7
names
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1D Array Object Declaration
var salaries: Array = new Array( );
salaries [ 0 ]
salaries [ 1 ]
salaries [ 2 ]
salaries [ 3 ]
salaries [ 4 ]
…
salaries
TypeName of array Constructor method
Note: The array is variable-sized. It starts with 0 elements.
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Array Assignment Statements
salaries[0] = 7;
7
salaries [ 0 ]
salaries [ 1 ]
salaries [ 2 ]
salaries [ 3 ]
salaries [ 4 ]
…
salaries
Name of array
Index Value of element
13
Example Array Statements
var base: int = 30000;
salaries[ 2 ] = 45000;
salaries[ 5 ] = base;
salaries[ 6 ] = base + 6000;
salaries[ 2 ] = salaries[ 2 ] + 4000;
trace( salaries [ 2 ] );
Output: 49000
49000
30000
36000
salaries [ 0 ]
salaries [ 1 ]
salaries [ 2 ]
salaries [ 3 ]
salaries [ 4 ]
salaries [ 5 ]
salaries [ 6 ]
…
30000base
14
Array Constructor Shortcuts
var numList : Array = new Array( 33, 2, 91, 12, 8 );
33
2
91
12
8
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
var numList : Array = [ 33, 2, 91, 12, 8 ];
OR
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Tracing an Array
trace(numList.toString( ));
33
2
91
12
8
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
Output: 33, 2, 91, 12, 8
16
Array Objects have a Length Property
trace(numList.length);
33
2
91
12
8
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList5
numList.length
Output: 5
17
Adding Elements to an Array
numList.push(11);
numList.unshift(20);
20
33
2
91
12
8
11
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList[5]
numList[6]
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
33
2
91
12
8
18
Adding Elements to an Array
numList.splice(3, 0, 44);
20
33
2
44
91
12
8
11
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList[5]
numList[6]
numList[7]
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList[5]
numList[6]
20
33
2
91
12
8
11
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Removing Elements from an Array
var n1: int = numList.pop( );var n2: int = numList.shift( );
// Now n1 = 11// and n2 = 20// and these elements are // removed from numList
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList[5]
33
2
44
91
12
8
20
Returning Elements from an Array
var list: Array = numList.slice(3,5);
// Now list = 91, 12, 8// but numList is not changed
numList[0]
numList[1]
numList[2]
numList[3]
numList[4]
numList[5]
33
2
44
91
12
8
Random Numbers
The random( ) method in the Math class returns a
random value between 0 and .9999999999999999
Example:
var rand: Number = Math.random( );
trace( "rand = " + rand );
21
Random Numbers
To obtain a random integer between 0 and 20,
multiply the result by 20 and then round the
result, using the round method, also in the Math
class.
Example:
var rand: Number = 20 * Math.random( );
rand = Math.round( rand );
trace( "rand = " + rand );22
