Arrays in Go

An array in Go is a collection of elements that all share the same data type. Arrays store multiple values in a single variable and are useful when you know the exact number of elements in advance.

Unlike slices, arrays in Go have a fixed size that cannot be changed after creation.

Declaring an Array

An array declaration includes the data type and the number of elements.

package main

import "fmt"

func main() {
    var numbers [5]int
    fmt.Println(numbers)
}

This creates an array of 5 integers. All values are initialized to 0 by default.

Initializing an Array with Values

You can assign values to an array at the time of declaration.

package main

import "fmt"

func main() {
    scores := [4]int{85, 90, 78, 88}
    fmt.Println(scores)
}

Each value is stored at a specific position (index) in the array.

Accessing Array Elements

Array elements are accessed using index numbers. Indexing in Go starts from 0.

package main

import "fmt"

func main() {
    scores := [4]int{85, 90, 78, 88}

    fmt.Println(scores[0])
    fmt.Println(scores[2])
}

Here, scores[0] accesses the first element, and scores[2] accesses the third element.

Updating Array Values

You can modify an array element by assigning a new value to its index.

package main

import "fmt"

func main() {
    scores := [4]int{85, 90, 78, 88}
    scores[1] = 95

    fmt.Println(scores)
}

The value at index 1 is updated from 90 to 95.

Array Length

The len() function returns the total number of elements in an array.

package main

import "fmt"

func main() {
    scores := [4]int{85, 90, 78, 88}
    fmt.Println("Length:", len(scores))
}

The length of an array is fixed and part of its type definition.

Looping Through an Array

Arrays are commonly processed using loops.

package main

import "fmt"

func main() {
    scores := [4]int{85, 90, 78, 88}

    for i := 0; i < len(scores); i++ {
        fmt.Println("Score:", scores[i])
    }
}

This loop prints each element stored in the array.

Real-World Example: Daily Sales

Arrays are useful when handling fixed-size datasets, such as daily sales for a week.

package main

import "fmt"

func main() {
    sales := [7]int{1200, 1500, 980, 1100, 1750, 1600, 1400}
    total := 0

    for i := 0; i < len(sales); i++ {
        total += sales[i]
    }

    fmt.Println("Weekly Sales:", total)
}

This program calculates the total sales for a week using an array.

Important Rules About Arrays

• Arrays have a fixed size
• The size is part of the array’s type
• All elements must be the same data type
• Arrays are stored in contiguous memory

Arrays vs Other Data Structures

Arrays are efficient and simple, but they lack flexibility. When you need a dynamic size, Go provides slices, which are built on top of arrays.

What’s Next?

In the next lesson, you will learn about Slices in Go, which are more flexible and widely used than arrays in real-world applications.