Using Arrays | Computer for GCSE/IGCSE - Year 11 PDF Download

Using Arrays

• Arrays serve as efficient containers for multiple values of the same data type.
• They find application in various tasks like maintaining student scores, computing averages, and handling inventory data.

Using variables in arrays

• Variables can act as indices in arrays, enabling access and modification of elements through iterative checks.
• This functionality proves valuable during array traversal using loops or conducting computations based on user input.

What is the first index value?

• The initial index in an array can either start at 0 or 1, influenced by the programming language and personal choice.
• Commonly used languages like Python, Java, and Visual Basic opt for 0 as the starting index.

Pseudocode example:

DECLARE scores[5] OF INTEGER
FOR i FROM 0 TO 4
INPUT scores[i]
ENDFOR

Python example:

scores = [0] * 5
for i in range(5):
scores[i] = int(input())

Java example:

int[] scores = new int[5];
Scanner scanner = new Scanner(System.in);
for (int i = 0; i < 5; i++) {
    scores[i] = scanner.nextInt();
}

Visual Basic example:

Dim scores(5) As Integer
For i As Integer = 0 To 4
   console.Writeline("Enter score: ")
    scores(i) = Console.ReadLine())
Next

Using Iteration

• Loops enable the assignment of values into arrays by iterating through each element and assigning a value to it.
• Similarly, iteration facilitates the retrieval of values from arrays by traversing through each element and executing operations or outputting the value.
• Nested iteration proves valuable in handling multi-dimensional arrays like 2D arrays, where iteration through rows and columns is necessary.

Pseudocode example:

DECLARE scores[3][3] OF INTEGER
FOR i FROM 0 TO 2
   FOR j FROM 0 TO 2
      INPUT scores[i][j]
   ENDFOR
ENDFOR
FOR i FROM 0 TO 2
   FOR j FROM 0 TO 2
      OUTPUT scores[i][j]
   ENDFOR
ENDFOR

Python example:

scores = [[0] * 3 for _ in range(3)]
for i in range(3):
    for j in range(3):
        scores[i][j] = int(input())
for i in range(3):
    for j in range(3):
        print(scores[i][j])

Java example:

int[][] scores = new int[3][3];
Scanner scanner = new Scanner(System.in);
for (int i = 0; i < 3; i++) {
    for (int j = 0; j < 3; j++) {
        scores[i][j] = scanner.nextInt();
    }
}
for (int i = 0; i < 3; i++) {
    for (int j = 0; j < 3; j++) {
        System.out.print(scores[i][j] + " ");
    }
    System.out.println();
}

Visual Basic example:

Dim scores(2, 2) As Integer
For i As Integer = 0 To 2
    For j As Integer = 0 To 2
        Console.Writeline("Enter score: ")
        scores(i, j) = Console.ReadLine())
    Next
Next
For i As Integer = 0 To 2
    For j As Integer = 0 To 2
        Console.Write(scores(i, j) & " ")
    Next
    Console.WriteLine()
Next