Accessing array elements in Go - Mini Project: Build & Apply

Accessing array elements

📖 Scenario: You are organizing a small fruit basket. You want to keep track of the fruits you have and check specific fruits by their position in the basket.

🎯 Goal: Learn how to create an array of fruits and access specific fruits by their position (index) in the array.

📋 What You'll Learn

Create an array of fruits with exact values

Create a variable to hold the index of the fruit to access

Access the fruit at the given index from the array

Print the accessed fruit

💡 Why This Matters

🌍 Real World

Arrays are used to store collections of items like fruits, names, or numbers where you want to access items by their position.

💼 Career

Understanding how to access array elements is fundamental for programming tasks such as data processing, user input handling, and working with lists in software development.

1

Create an array of fruits

Create an array called fruits with these exact values: "Apple", "Banana", "Cherry", "Date", "Elderberry".

Go

// Your code here

Hint

Use the syntax varName := [size]type{values} to create an array.

2

Create an index variable

Create an integer variable called index and set it to 2 to select the third fruit in the array.

Go

package main

func main() {
    fruits := [5]string{"Apple", "Banana", "Cherry", "Date", "Elderberry"}
    // Your code here
}

Hint

Use variableName := value to create and set a variable.

3

Access the fruit at the given index

Create a variable called selectedFruit and set it to the fruit at position index in the fruits array.

Go

package main

func main() {
    fruits := [5]string{"Apple", "Banana", "Cherry", "Date", "Elderberry"}
    index := 2
    // Your code here
}

Hint

Use arrayName[index] to access an element at a specific position.

4

Print the selected fruit

Use fmt.Println to print the value of selectedFruit.

Go

package main

import "fmt"

func main() {
    fruits := [5]string{"Apple", "Banana", "Cherry", "Date", "Elderberry"}
    index := 2
    selectedFruit := fruits[index]
    // Your code here
}

Hint

Use fmt.Println(variableName) to print the value to the screen.

Practice

1. What is the index of the first element in a Go array?

easy

A. 1

B. Depends on the array size

C. -1

D. 0

Solution

1. Step 1: Understand Go array indexing

   In Go, arrays start indexing from 0, meaning the first element is at index 0.

2. Step 2: Confirm the first element's index

   The first element is always accessed with index 0, not 1 or any other number.

3. Final Answer:

   0 -> Option D

4. Quick Check:

   First element index = 0 [OK]

Hint: Remember, Go arrays start counting at zero [OK]

Common Mistakes:

• Thinking indexing starts at 1
• Assuming negative indexes are valid
• Believing index depends on array size

2. Which of the following is the correct way to access the third element of an array named arr in Go?

easy

A. arr[3]

B. arr[2]

C. arr(2)

D. arr{2}

Solution

1. Step 1: Recall Go array indexing syntax

   Go uses square brackets with zero-based indexing to access elements, so the third element is at index 2.

2. Step 2: Identify correct syntax

   arr[2] accesses the third element; arr[3] accesses the fourth, arr(2) and arr{2} are invalid syntax.

3. Final Answer:

   arr[2] -> Option B

4. Quick Check:

   Third element = arr[2] [OK]

Hint: Use square brackets and zero-based index [OK]

Common Mistakes:

• Using parentheses instead of brackets
• Using 1-based index
• Using curly braces for access

3. What will be the output of this Go code?

arr := [4]int{10, 20, 30, 40}
fmt.Println(arr[1])

medium

A. 10

B. 40

C. 20

D. 30

Solution

1. Step 1: Identify the array elements and their indexes

   The array is [10, 20, 30, 40], indexed 0 to 3. Index 1 corresponds to the second element, 20.

2. Step 2: Determine the printed value

   arr[1] accesses the element 20, so fmt.Println prints 20.

3. Final Answer:

   20 -> Option C

4. Quick Check:

   arr[1] = 20 [OK]

Hint: Remember index 1 is second element [OK]

Common Mistakes:

• Printing arr[0] instead
• Confusing index 1 with 2
• Expecting output as 30 or 40

4. What is wrong with this Go code snippet?

arr := [3]int{1, 2, 3}
fmt.Println(arr[3])

medium

A. Index 3 is out of bounds for the array

B. Array declaration syntax is incorrect

C. fmt.Println cannot print array elements

D. The array size should be 4

Solution

1. Step 1: Check array size and valid indexes

   The array has size 3, so valid indexes are 0, 1, and 2 only.

2. Step 2: Identify the error in accessing arr[3]

   Accessing arr[3] tries to get the fourth element, which does not exist, causing an out-of-bounds runtime error.

3. Final Answer:

   Index 3 is out of bounds for the array -> Option A

4. Quick Check:

   Valid indexes: 0 to 2 only [OK]

Hint: Array indexes go from 0 to length-1 [OK]

Common Mistakes:

• Using index equal to array length
• Thinking fmt.Println can't print elements
• Assuming array size auto-expands

5. Given the array arr := [5]int{5, 10, 15, 20, 25}, which code snippet correctly sums the first three elements?

hard

A. sum := arr[0] + arr[1] + arr[2]

B. sum := arr[1] + arr[2] + arr[3]

C. sum := arr[0] + arr[2] + arr[3]

D. sum := arr[2] + arr[3] + arr[4]

Solution

1. Step 1: Identify the first three elements

   The first three elements are at indexes 0, 1, and 2, which are 5, 10, and 15 respectively.

2. Step 2: Check which option sums these elements

   sum := arr[0] + arr[1] + arr[2] sums arr[0], arr[1], and arr[2], which is correct. Other options include elements beyond the first three.

3. Final Answer:

   sum := arr[0] + arr[1] + arr[2] -> Option A

4. Quick Check:

   Sum first three = arr[0]+arr[1]+arr[2] [OK]

Hint: Sum elements at indexes 0, 1, and 2 for first three [OK]

Common Mistakes:

• Starting sum at index 1
• Skipping elements
• Including elements beyond first three