10.2 Arrays

Arrays are fundamental data structures in computer science used to store a collection of elements of the same data type. These elements are stored in contiguous memory locations and can be accessed using an index.

Array Concepts

• Index: A numerical identifier used to access individual elements within an array. Array indices typically start from 0.
• Array Size: The total number of elements an array can hold.
• Array Element: A single value stored within an array.

Array Declaration and Initialization

In many programming languages, arrays are declared with a specific data type and size. Here's a general representation:

    data_type [array_name] = {element1, element2, ..., elementN};
    

For example, an array of 5 integers could be declared as int numbers[5].

Array Access

Elements in an array are accessed using their index within square brackets. The index starts from 0 for the first element.

For example, numbers[0] refers to the first element, numbers[1] refers to the second, and so on.

Pseudo-code for Array Processing

Here are some examples of pseudo-code for common array processing tasks:

1. Accessing an Element

1. Define an array with a specific size and data type.
2. Assign a value to an element using its index.
3. To retrieve a value, use the index within square brackets.

Step	Action
1	Define array numbers of size 5 as integers.
2	Assign value 10 to numbers[0].
3	Retrieve value at index 1 using numbers[1].

2. Iterating Through an Array

Loops are commonly used to process each element in an array.

    FOR i = 0 TO array_size - 1 DO
        Process array[i]
    END FOR
    

Step	Action
1	Initialize a loop counter i to 0.
2	Repeat the following steps until i is equal to array_size - 1.
3	Access the element at index i of the array.
4	Perform the desired operation on the accessed element.
5	Increment i by 1.

3. Finding the Maximum Value

The following pseudo-code demonstrates how to find the maximum value in an array.

    maximum = array[0]
    FOR i = 1 TO array_size - 1 DO
        IF array[i] > maximum THEN
            maximum = array[i]
        END IF
    END FOR
    RETURN maximum
    

Step	Action
1	Assume the first element of the array is the maximum.
2	Iterate through the remaining elements of the array.
3	For each element, compare it with the current maximum.
4	If the current element is greater than the maximum, update the maximum.
5	After iterating through all elements, the variable 'maximum' will hold the largest value in the array.

4. Calculating the Sum of Array Elements

Pseudo-code to calculate the sum of all elements in an array:

    sum = 0
    FOR i = 0 TO array_size - 1 DO
        sum = sum + array[i]
    END FOR
    RETURN sum
    

Step	Action
1	Initialize a variable sum to 0.
2	Iterate through each element of the array.
3	Add the current element to the sum.
4	After iterating through all elements, the variable sum will contain the total sum of all elements in the array.