What Is an Array?

An array is a data structure used to store multiple values of the same data type under one variable name.

Instead of creating many separate variables, an array allows a program to store and manage related data together.

Example:

Instead of writing:

score1 ← 85
score2 ← 90
score3 ← 78

We can use an array:

scores[1] ← 85
scores[2] ← 90
scores[3] ← 78

Here, scores is the array name, and each value is accessed using an index number.

Why Arrays Are Used

Arrays help programs:

• Store large amounts of related data

• Organize information efficiently

• Simplify program code

• Process data using loops

Arrays are commonly used when working with lists of data such as:

• Student marks

• Temperature readings

• Product prices

One-Dimensional Arrays (1D Arrays)

A one-dimensional array stores data in a single row or list.

Example:

marks[1] ← 75
marks[2] ← 80
marks[3] ← 65
marks[4] ← 90

This array stores four student marks.

We can access each value using its index position.

Example:

OUTPUT marks[2]

Output: 80

Using Arrays with Loops

Arrays are often used together with loops.

Example pseudocode:

FOR i ← 1 TO 5
    INPUT marks[i]
NEXT i

This loop allows the program to input multiple values into the array efficiently.

Two-Dimensional Arrays (2D Arrays)

A two-dimensional array stores data in rows and columns, similar to a table.

Example:

marks[1,1] ← 75
marks[1,2] ← 80
marks[2,1] ← 65
marks[2,2] ← 90

This structure is useful when storing table-like data, such as:

• Student marks for multiple subjects

• Game boards

• Matrices

Example of a 2D Array Table

StudentMathScienceStudent 17580Student 26590

Each value can be accessed using two indices: row and column.

Advantages of Arrays

Arrays provide several benefits:

✅ Efficient storage of related data

✅ Easy data processing with loops

✅ Organized data structure

✅ Simplifies program design

Because of these advantages, arrays are widely used in programming and data processing.

Exam Tip (2210 / 0478)

Students are commonly asked to:

• Define arrays

• Explain 1D and 2D arrays

• Write pseudocode using arrays and loops

A common exam question is:

Explain one advantage of using arrays in programming.

Practice Question

Explain one advantage of using arrays instead of multiple variables.

Answer

Arrays allow programs to store many related values using a single variable name, making programs easier to manage.

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