Array modification (push, pop, shift, unshift) in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add the number 5 to the end of the array.

Ruby

numbers = [1, 2, 3, 4]
numbers.[1](5)
puts numbers.inspect

Drag options to blanks, or click blank then click option'

Aunshift

Bpop

Cpush

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop removes the last element instead of adding.

Using shift removes the first element.

Using unshift adds to the beginning, not the end.

The push method adds an element to the end of the array.

2fill in blank

medium

Complete the code to remove the first element from the array.

Ruby

fruits = ['apple', 'banana', 'cherry']
removed = fruits.[1]()
puts removed
puts fruits.inspect

Drag options to blanks, or click blank then click option'

Apop

Bunshift

Cpush

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop removes the last element, not the first.

Using push or unshift add elements instead of removing.

The shift method removes and returns the first element of the array.

3fill in blank

hard

Fix the error in the code to add 'orange' to the beginning of the array.

Ruby

colors = ['red', 'green', 'blue']
colors.[1]('orange')
puts colors.inspect

Drag options to blanks, or click blank then click option'

Aunshift

Bpop

Cpush

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using push adds to the end, not the beginning.

Using pop or shift remove elements instead of adding.

The unshift method adds an element to the beginning of the array.

4fill in blank

hard

Fill both blanks to remove the last element and add 'kiwi' to the beginning of the array.

Ruby

basket = ['apple', 'banana', 'cherry']
basket.[1]()
basket.[2]('kiwi')
puts basket.inspect

Drag options to blanks, or click blank then click option'

Apop

Bpush

Cunshift

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using shift instead of pop removes the first element.

Using push instead of unshift adds to the end.

pop removes the last element, and unshift adds an element to the beginning.

5fill in blank

hard

Fill all three blanks to add 10 to the end, remove the first element, and add 5 to the beginning of the array.

Ruby

nums = [1, 2, 3]
nums.[1](10)
removed = nums.[2]()
nums.[3](5)
puts nums.inspect
puts removed

Drag options to blanks, or click blank then click option'

Apop

Bshift

Cunshift

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up pop and shift for removing elements.

Using push instead of unshift to add at the beginning.

push adds to the end, shift removes the first element, and unshift adds to the beginning.

Practice

1. Which Ruby array method adds an element to the end of the array?

easy

A. shift

B. pop

C. push

D. unshift

Solution

1. Step 1: Understand the purpose of push

   The push method adds an element to the end of an array.

2. Step 2: Compare with other methods

   pop removes the last element, shift removes the first, and unshift adds to the front.

3. Final Answer:

   push -> Option C

4. Quick Check:

   push adds to end [OK]

Hint: Remember: push = add end, unshift = add front [OK]

Common Mistakes:

• Confusing push with pop
• Mixing shift and unshift
• Thinking pop adds elements

2. Which of the following is the correct syntax to remove the first element from an array arr in Ruby?

easy

A. arr.shift()

B. arr.pop()

C. arr.unshift()

D. arr.push()

Solution

1. Step 1: Identify method to remove first element

   The shift method removes and returns the first element of an array.

2. Step 2: Check syntax correctness

   Calling arr.shift() correctly removes the first element.

3. Final Answer:

   arr.shift() -> Option A

4. Quick Check:

   shift removes first element [OK]

Hint: shift removes first, pop removes last [OK]

Common Mistakes:

• Using pop to remove first element
• Calling unshift to remove elements
• Forgetting parentheses

3. What will be the output of the following Ruby code?

arr = [1, 2, 3]
arr.push(4)
arr.shift
p arr

medium

A. [1, 2, 3]

B. [1, 2, 3, 4]

C. [4, 1, 2, 3]

D. [2, 3, 4]

Solution

1. Step 1: Execute push(4) on array

   Adding 4 to the end changes array from [1, 2, 3] to [1, 2, 3, 4].

2. Step 2: Execute shift to remove first element

   Removing first element (1) results in [2, 3, 4].

3. Final Answer:

   [2, 3, 4] -> Option D

4. Quick Check:

   push adds end, shift removes front = [2, 3, 4] [OK]

Hint: push adds end, shift removes front, watch order [OK]

Common Mistakes:

• Ignoring shift effect
• Thinking push adds front
• Confusing pop with shift

4. The following Ruby code is intended to add 0 to the front of the array nums and then remove the last element. What is the error?

nums = [1, 2, 3]
nums.unshift(0)
nums.pop()

medium

A. No error; code works correctly

B. pop() should be called before unshift()

C. unshift() does not add elements to array

D. pop() removes the first element, not the last

Solution

1. Step 1: Understand unshift(0) effect

   This adds 0 to the front, changing [1, 2, 3] to [0, 1, 2, 3].

2. Step 2: Understand pop() effect

   This removes the last element (3), resulting in [0, 1, 2].

3. Final Answer:

   No error; code works correctly -> Option A

4. Quick Check:

   unshift adds front, pop removes last = correct [OK]

Hint: unshift adds front, pop removes last, order matters [OK]

Common Mistakes:

• Thinking pop removes first element
• Believing unshift does not add
• Swapping order of operations unnecessarily

5. Given the array data = [10, 20, 30], which sequence of method calls will result in [5, 10, 20]?

hard

A. data.push(5).shift()

B. data.unshift(5).pop()

C. data.shift().unshift(5)

D. data.pop().unshift(5)

Solution

1. Step 1: Apply unshift(5) to add 5 at front

   Array changes from [10, 20, 30] to [5, 10, 20, 30].

2. Step 2: Apply pop() to remove last element

   Removing last element (30) results in [5, 10, 20].

3. Final Answer:

   data.unshift(5).pop() -> Option B

4. Quick Check:

   unshift adds front, pop removes last = [5, 10, 20] [OK]

Hint: Add front with unshift, then remove last with pop [OK]

Common Mistakes:

• Using push instead of unshift
• Removing first element instead of last
• Chaining methods incorrectly