Chapter 6 : Arrary Flashcards

1
Q

List out 2 categories that data types in C#

A
  1. Values Types ( x = “Hello” )
  2. Reference Types
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2
Q

What actually holds the data in a value type ?

A
  1. Value Type of Variable
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3
Q

What will compiler allocates when I declare a value type variable?

A
  1. The compiller will allocate a chunk of memory that is big enough for the variable
  • When I’m working with a value type, I’m actually using a variable that holds a piece of data
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4
Q

List out 2 things when I work with a reference type

A
  1. An object that is created in memory
  2. A variable that references the project
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5
Q

What does array stores?

A
  1. A group of the same data type together in memory
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6
Q

What data isn’t ideal for array?

A
  1. Storing and Processing lists of data
  • Each variable can only store 1 data
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7
Q

What type of data type is array? ( Value Type / References Type )

A
  1. Reference Type Objects
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8
Q

What do I need to do to create an array?

A
  1. Declare a reference type object
  2. Create the obkect and associate it with the reference variable
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9
Q

What is the format for array?

A
  1. dataType[] arraryName;

int[] numbersArray

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10
Q

What is the format for adding new values for array?

A
  1. arrayName = new DataType[ArrarySize]

numbersArrary = new int[6]

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11
Q

What is the storage location known as in array?

A
  1. Elements
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12
Q

What is noun for the unique number assigned at each element inside an array?

A
  1. Subscript
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13
Q

What is the subscript value for the first elements?

A
  1. 0
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14
Q

How to create a array with assigning the maximum number of elements in it?

A

const int size = 5;
int numbers = new int[size];

numbers[0] = 1;
numbers[1] = 2;
numbers[2] = 3;
numbers[3] = 4;
numbers[4] = 5;

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15
Q

How to get the third element of array?

A
  1. number[2]
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16
Q

List out 3 ways to initialize array

A
  1. int[] num = { 10 , 20 , 30 }
  2. int[] num = new int { 10, 20, 30 }
  3. const int size = 3
    int[] num = new int[size] {10,20,30};
17
Q

How to loop through arrary with adding value 99 into the array 3 times?

A

const int size = 3;
int[] myValues = new int[size];
for ( int i = 0; i < size; i++ )
{
myValues[i] = 99;
}

  • Please make sure that this code i < size musn’t be i <= size since the array value is only 0 , 1 , 2 . 3 will return an exception
18
Q

What is the length property does?

A
  1. Set the number of elements in the array
19
Q

How to set 25 elements in the array? How to output the length of an array?

A
  1. double[] temp = new double[25]
  2. MessageBox.Show(temperatures.Length.ToString());
20
Q

How to use the length property to loop through every single item in an array?

A

for ( int i = 0; i < tem.Length; i ++ )
{
MessageBox.Show(tem[i].ToString());
}

21
Q

What is the foreach loop used for?

A
  1. Special loop used to simplify array processing
  2. It is designed to work a temporary, read-only variable known as iteration variable
22
Q

What is the format for foreach loop?

A

foreach ( Type VariableName in ArraryName )
{
statement(s);
}

  • Type = data type of array
    VariableName = name of temporary iteration variable
23
Q

How to use foreach loop through the arrary
int[] numbers = { 3 , 6 , 9 }?

A

int[] numbers = { 3 , 6 , 9 }
foreach ( int val in numbers )
{
MessageBox.Show(val.ToString());
}

24
Q

How to use a method that passed in array as argument and show the content inside it?

A

string[] people = { “Bill” , “Jill”}
showArrary(people);

private void showArray(string[] strArray)
{
foreach ( string str in strArrary )
{
MessageBox.Show(str);
}
}

25
How to create a program that searches value 30 inside the array and if the value is found, its positionis returned; otherwise -1 is returned
int[] sArray = new int[] { 10, 20, 30, 40, 50}; bool found = false; int index = 0; int position = -1; while(!found && index < sArray.Length) { if ( sArray[index] == 30 ) { found = true; position = index; MessageBox.Show(position.ToString()); } index++; }
26
How to use for and foreach loop to create a second array and copy the individual element of the source array to the target array?
for ( int i = 0 ; i < firstArray.Length; i++ ) { secondArray[i] = firstArrary[i]; } int[] firstArray = { 3, 6, 9 }; int[] secondArray = new int[firstArray.Length]; int index = 0; foreach ( var num in firstArray ) { secondArray[index] = num index ++; }
27
How to compare array with length and elements?
if (firstArray.Length != secondArray.Length) { return false; } if (firstArray[index] != secondArray[index]) { return false ; }
28
How to total up the value of an array?
for (int i = 0; index < units.length; index++ ) { total += units[index]; }
29
How to find out the highes value in an array?
int[] numbers = { 8 , 1 , 12 , 6 , 2 } int highest = numbers[0]; for (int i = 1; i < numbers.Length; i ++ ) { if (numbers[index] > highest) { highest = numbers[index]; } }
30
What is the difference between list and array?
1. List can be resized dynamically but arrays can't 2. Proivides the methods to add, search, sort and manipulate lists
31
31
What generic class is list under?
1. System.Collections.Generic
31
How to add 26, 15,12 into list numList?
numList.Add(26); numList.Add(15); numList.Add(12);
32
How to insert number 53 into the second element?
numList.Insert(2,53);
32
How to insert a list into another list?
int[] num = {11,22,33} numList.InsertRange(4,num);
32
How to remove an element 11 from a list?
numList.Remove(11);
32
How to remove the element in a index of 4 in list?
numList.RemoveAt(4);
33
List out some other methods in list ( 5 )
1. Clear() - Remove all items in list 2. Find() - Search item in list 3. Sort() - Sort list in ascending order 4. Reverse - Reverse items in list 5. Count - Returns the size of list