Go Arrays

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Go Arrays

In Go, an array is a data structure used to store multiple values of the same type in a single variable. Instead of creating separate variables for each value, arrays allow you to manage collections of data efficiently.

What Is an Array?

An array:

• Holds a fixed number of elements
• Stores elements of the same data type
• Uses index-based access (starting from 0)

Important: The size of an array in Go is fixed once declared and cannot be changed.

Declaring Arrays in Go

There are two common ways to declare arrays:

1. Using var

var scores = [4]int{85, 90, 78, 92}

2. Using Short Declaration (:=)

marks := [3]int{70, 80, 95}

Letting Go Infer Array Length

You can allow the compiler to determine the array size using ....

package main import "fmt" func main() { primes := [...]int{2, 3, 5, 7, 11} fmt.Println("Prime numbers:", primes) }

Prime numbers: [2 3 5 7 11]

Working with Arrays

Example: Declaring and Printing Arrays

package main import "fmt" func main() { temperatures := [3]float64{36.5, 37.0, 36.8} cities := [...]string{"Chennai", "Delhi", "Mumbai"} fmt.Println("Temperatures:", temperatures) fmt.Println("Cities:", cities) }

Temperatures: [36.5 37 36.8] Cities: [Chennai Delhi Mumbai]

Accessing Array Elements

Array elements are accessed using their index.

package main import "fmt" func main() { prices := [4]int{100, 200, 300, 400} fmt.Println("First price:", prices[0]) fmt.Println("Last price:", prices[3]) }

First price: 100 Last price: 400

Modifying Array Elements

You can update elements by assigning a new value to a specific index.

package main import "fmt" func main() { stock := [3]int{10, 20, 30} stock[1] = 50 // Update second element fmt.Println("Updated stock:", stock) }

Updated stock: [10 50 30]

Array Initialization and Default Values

If elements are not initialized, Go assigns default values:

• int → 0
• string → ""
• bool → false

package main import "fmt" func main() { numbers := [5]int{} // All values default to 0 partial := [5]int{1, 2, 3} // Remaining values default to 0 fmt.Println("Numbers:", numbers) fmt.Println("Partial:", partial) }

Numbers: [0 0 0 0 0] Partial: [1 2 3 0 0]

Initializing Specific Elements

You can initialize selected indices directly.

package main import "fmt" func main() { data := [5]int{0: 10, 3: 40} fmt.Println("Custom array:", data) }

Custom array: [10 0 0 40 0]

Explanation:

• Index 0 → 10
• Index 3 → 40
• Other elements default to 0

Finding the Length of an Array

Use the built-in len() function to get the number of elements.

package main import "fmt" func main() { languages := [...]string{"Go", "Python", "JavaScript"} fmt.Println("Number of languages:", len(languages)) }

Number of languages: 3

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