OBJECTIVE

• Define and use 2D arrays.  

DISCUSSION

2D Array 

• Like a table
• Its an array of arrays
• Example

	0	1	2	...	N
0	a	b	c	...	d
1	e	f	g	...	h
2	i	j	k	...	l
...	...	...	...	...	...
M	m	n	o	...	p

Creating and Using Arrays

• Create an array to hold arrays
• Create individual arrays for the main array
• Example:   

 

var sRow0 = new Array()

var sRow1 = new Array()

var sRow2 = new Array()

var sTable = new Array(sRow0, sRow1, sRow2)

 

 

sTable[0][0] = "Row0Col0"

sTable[0][1] = "Row0Col1"

sTable[2][2] = "Row2Col2"

sTable[2][5] = "Row2Col5"

 

alert(sTable[2][5])

alert(sTable.length)

alert(sTable[0].length)

alert(sTable[1].length)

alert(sTable[2].length)

 

EXERCISES

#1 to #4 are all related. 

1.  Create a 10-by-10 array that holds the multiplication table.  For example, cell (2,3) should hold the value 6. 

2. Create a function to set the values of the array in #1.  You will need to use a for loop in a for loop.

3. Create a function to display the array in #1. 

4.  Create a program to demonstrate #1 to #3.

5.  Create a general function that accepts any 2D array and returns a string with the contents of the array in tabular form.

6.  Write code that initializes a 10 by 10 array of characters so that all elements are "X" except those on the diagonal which are set to "O".  If the array is displayed it would look like:

OXXXXXXXXX
XOXXXXXXXX
XXOXXXXXXX
XXXOXXXXXX
XXXXOXXXXX
XXXXXOXXXX
XXXXXXOXXX
XXXXXXXOXX
XXXXXXXXOX
XXXXXXXXXO

LINKS AND HELP