Go – Create Slice From Array

In Go, slices can be created from arrays by referencing a portion of the array. Slices are lightweight and dynamic views over an array, allowing you to access and manipulate elements without copying the data. This makes them an efficient way to work with subsets of an array.

In this tutorial, we will explore how to create slices from arrays in Go, demonstrate practical examples, and provide detailed explanations for each example.

Steps to Create a Slice From an Array

Declare an Array: Define an array with the desired size and type.
Use Slicing Syntax: Create a slice by specifying the range of indices using array[start:end].
Include Start Index: The start index is inclusive.
Exclude End Index: The end index is exclusive.

Examples of Creating a Slice From an Array

1. Basic Slice Creation

This example demonstrates how to create a slice from an array:

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package main

import "fmt"

func main() {
    // Declare an array
    arr := [5]int{10, 20, 30, 40, 50}

    // Create a slice from the array
    slice := arr[1:4]

    // Print the array and the slice
    fmt.Println("Array:", arr)
    fmt.Println("Slice:", slice)
}

Explanation

Array Declaration: The array arr is initialized with five integers.
Slice Creation: The slice slice is created using the syntax arr[1:4], which includes elements at indices 1, 2, and 3.
Array and Slice Independence: The slice references the same underlying array, meaning changes to the slice will reflect in the array and vice versa.

Output

2. Slice the Entire Array

This example demonstrates how to create a slice that includes all elements of the array:

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package main

import "fmt"

func main() {
    // Declare an array
    arr := [5]int{10, 20, 30, 40, 50}

    // Create a slice of the entire array
    slice := arr[:]

    // Print the array and the slice
    fmt.Println("Array:", arr)
    fmt.Println("Slice:", slice)
}

Explanation

Array Declaration: The array arr is initialized with five integers.
Slice Creation: The slice slice is created using arr[:], which includes all elements of the array.
Same Underlying Array: The slice and the array share the same underlying data, making them interdependent.

Output

3. Modify Slice and Observe Array

This example demonstrates how modifying a slice affects the underlying array:

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package main

import "fmt"

func main() {
    // Declare an array
    arr := [5]int{10, 20, 30, 40, 50}

    // Create a slice from the array
    slice := arr[1:4]

    // Modify the slice
    slice[0] = 99

    // Print the array and the slice
    fmt.Println("Array after modification:", arr)
    fmt.Println("Slice after modification:", slice)
}

Explanation

Array Declaration: The array arr is initialized with five integers.
Slice Creation: The slice slice is created using arr[1:4], referencing a subset of the array.
Modify Slice: The first element of the slice is modified to 99, which updates the corresponding element in the array.
Shared Data: Since the slice and array share the same underlying data, changes to one reflect in the other.

Output

Points to Remember

Shared Data: Slices created from arrays share the same underlying array, so changes in one affect the other.
Index Boundaries: Ensure the slice indices are within the valid range of the array to avoid runtime errors.
Flexible Slicing: Use slicing syntax to create views of any subset of the array.
Efficient Memory Usage: Slices avoid copying data and are lightweight references to an array.

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Go – Create Slice From Array