1. Managing Collections of Data
Imran Rashid
CTO at ManiWeber Technologies

2. Outline
Simple Array
Multidimensional Arrays
Generic

3. Simple Array

4. datatype[] arrayName;
Simple Array
An array stores a fixed-size sequential collection of elements of the same type
All arrays consist of contiguous memory locations
A specific element in an array is accessed by an index
The lowest address corresponds to the first element and the highest address to the last element
Declaring Arrays
datatype[] arrayName;
double[] threeHeights;

5. double[] heights = new double[10];
Simple Array
Initializing an Array
Declaring an array does not initialize the it in the memory
When the array variable is initialized, you can assign values to the array
Array is a reference type, so you need to use the new keyword to create an instance of the array
double[] heights = new double[10];
string[] colors = new string[7];
int[] ages = new int[3];

6. Simple Array Assigning Values to an Array
double[] balance = new double[10];
balance[0] = ;
double[] balance = { , , };
int[] marks = new int[5] { 99, 98, 92, 97, 95 };
int[] marks = new int[] { 99, 98, 92, 97, 95 };
int[] marks = new int[] { 99, 98, 92, 97, 95 }; int[] score = marks;

7. Simple Array Console.WriteLine() Array of Arguemnts Iterating Arrays
foreach
for
Array Behaviors
Sum() : int
Average() : double
Passing Arrays to Functions

8. Multidimensional Arrays

9. Multidimensional Arrays
Multidimensional arrays are also called rectangular array
Multidimensional Arrays
Initializing Two-Dimensional Arrays
string[ , ] names;
int[ , , ] marks;
int[ , ] a = new int[3, 4] {
{0, 1, 2, 3} , /* initializers for row indexed by 0 */
{4, 5, 6, 7} , /* initializers for row indexed by 1 */
{8, 9, 10, 11} /* initializers for row indexed by 2 */ };

10. Multidimensional Arrays
Example (Declaring)
int[ , ] m = new int[3, 4];
Column 01
[0]
Column 02
[1]
Column 03
[2]
Column 04
[3]
Row 01
m[0][0]
m[0][1]
m[0][2]
m[0][3]
Row 02
m[1][0]
m[1][1]
m[1][2]
m[1][3]
Row 03
m[2][0]
m[2][1]
m[2][2]
m[2][3]

11. Multidimensional Arrays
Initializing Arrays (guess the addresses)
int[ , ] m = new int[3, 4] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};
Column 01
[0]
Column 02
[1]
Column 03
[2]
Column 04
[3]
Row 01 1 2 3 4
Row 02 5 6 7 8
Row 03 9 10 11 12

12. Multidimensional Arrays
Sections Array 3 X 3
top left, top center, top right
middle left, middle center, middle right
bottom left, bottom center, bottom right
Tic Tac Toe Array 3 X 3
0,0
0,1
0,2
1,0
1,1
1,2
2,0
2,1
2,2
0,0
0,1
0,2
0,0
1,0
2,0
0,1
1,1
2,1
0,2
1,2
2,2
1,0
1,1
1,2
2,0
2,1
2,2

13. Generic

14. List<int> intList = new List<int>();
Generic
List
An array has a fixed number of items as we seen before
Once you declared it, can’t change the number of items
You can set an item to null but if an array has 3 items it always has 3 items
In contrast, the List class let you create resizable array
It let you add and remove items as you need to and can accommodate large amount of data
This will introduce a new style of programming known as generic data typing
List<int> intList = new List<int>();
var intList = new List<int>();

15. Generic Adding Items Manually Iterating List List Behaviors
foreach
for
List Behaviors
Add(T) – at the end
AddRange() – collection at the end
Remove(T) – remove first occurrence
RemoveAt(Index) – remove from a specific index
Sort() – sorts all the elements
Passing List to Functions

16. Q1: Difference b/w collection and generics
ASSIGNMENT
Submission Date 29/10/2018 & in written form
Q1: Difference b/w collection and generics
Q2: ArrayList with 2 examples
Q3: Dictionary with 2 examples
Q4: Hashtable with 2 examples

17. Any ?