Go – Subslice

In Go, you can create a subslice from an existing slice by specifying a range of indices. This operation does not copy the underlying data but instead creates a new view into the original slice.

In this tutorial, we will explore how to create subslices in Go with practical examples and detailed explanations.

Steps to Create a Subslice

  • Use Slicing Syntax: Use the syntax slice[start:end] to specify the range of indices for the subslice.
  • Understand Index Boundaries: The range includes the start index but excludes the end index.
  • Preserve the Original Slice: The subslice references the same underlying array as the original slice.

Examples of Creating a Subslice

1. Create a Subslice from a Slice of Integers

This example demonstrates how to create a subslice from a slice of integers:

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package main

import "fmt"

func main() {
    // Declare and initialize a slice
    numbers := []int{10, 20, 30, 40, 50}

    // Create a subslice from index 1 to 4
    subslice := numbers[1:4]

    // Print the original slice and subslice
    fmt.Println("Original Slice:", numbers)
    fmt.Println("Subslice:", subslice)
}

Explanation

  1. Initialize Slice: The slice numbers is initialized with five elements.
  2. Create Subslice: The subslice is created using numbers[1:4], which includes elements at indices 1, 2, and 3.
  3. Print Results: The original slice and the subslice are printed to show the result.

Output

Original Slice: [10 20 30 40 50]
Subslice: [20 30 40]

2. Create a Subslice from a Slice of Strings

This example demonstrates how to create a subslice from a slice of strings:

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package main

import "fmt"

func main() {
    // Declare and initialize a slice
    words := []string{"apple", "banana", "cherry", "date", "elderberry"}

    // Create a subslice from index 2 to the end
    subslice := words[2:]

    // Print the original slice and subslice
    fmt.Println("Original Slice:", words)
    fmt.Println("Subslice:", subslice)
}

Explanation

  1. Initialize Slice: The slice words is initialized with five elements.
  2. Create Subslice: The subslice is created using words[2:], which includes elements from index 2 to the end of the slice.
  3. Print Results: The original slice and the subslice are printed to show the result.

Output

3. Modify the Subslice and Observe the Original Slice

This example demonstrates how modifying a subslice affects the original slice:

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package main

import "fmt"

func main() {
    // Declare and initialize a slice
    numbers := []int{10, 20, 30, 40, 50}

    // Create a subslice
    subslice := numbers[1:4]

    // Modify the subslice
    subslice[0] = 99

    // Print the original slice and subslice
    fmt.Println("Original Slice after modification:", numbers)
    fmt.Println("Subslice after modification:", subslice)
}

Explanation

  1. Shared Memory: The subslice shares the same underlying array as the original slice.
  2. Modify Subslice: Changing an element in the subslice also modifies the corresponding element in the original slice.
  3. Print Results: Both the original slice and the subslice reflect the modification.

Output

Points to Remember

  • Index Boundaries: The slicing syntax includes the start index but excludes the end index.
  • Shared Memory: Subslices share the same underlying array as the original slice, so changes to a subslice affect the original slice.
  • Performance: Creating a subslice is efficient since it does not copy the underlying data.
  • Bounds Checking: Ensure that the indices used for slicing are within the valid range of the original slice.