Array Insertion at End in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to append a value to the end of the slice.

DSA Go

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

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

A4

B5

C6

D7

Attempts:

3 left

💡 Hint

Common Mistakes

Using append without assignment back to the slice.

Appending a value not matching the slice type.

Appending 4 adds it to the end of the slice, resulting in [1 2 3 4].

2fill in blank

medium

Complete the code to add the value 10 at the end of the slice.

DSA Go

data := []int{5, 6, 7}
data = append(data, [1])
fmt.Println(data)

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

A8

B11

C10

D9

Attempts:

3 left

💡 Hint

Common Mistakes

Appending a wrong number.

Not assigning the result of append back to the slice.

Appending 10 adds it to the end, resulting in [5 6 7 10].

3fill in blank

hard

Fix the error in the code to correctly append 15 to the slice.

DSA Go

values := []int{10, 11, 12}
values = append([1], 15)
fmt.Println(values)

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

Avalue

Bvalues

Cvals

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name in append.

Forgetting to assign append result back to the slice.

The slice variable is 'values', so append must use it to add 15.

4fill in blank

hard

Fill both blanks to append 20 to the slice and print the result.

DSA Go

nums := []int{16, 17, 18}
nums = [1](nums, [2])
fmt.Println(nums)

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

Aappend

B19

C20

Dadd

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong function name instead of append.

Adding the wrong value.

Use append to add 20 to nums, resulting in [16 17 18 20].

5fill in blank

hard

Fill all three blanks to append 25 to the slice and print it.

DSA Go

arr := []int{21, 22, 23}
arr = [1](arr, [2])
fmt.[3](arr)

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

Aappend

B25

CPrintln

DPrint

Attempts:

3 left

💡 Hint

Common Mistakes

Using fmt.Print instead of fmt.Println.

Appending wrong value or forgetting to assign back.

Use append to add 25 and fmt.Println to print the slice [21 22 23 25].

Practice

1. What happens when you insert an element at the end of a fixed-size array in Go?

easy

A. You cannot insert because arrays have fixed size

B. The element replaces the first element

C. The element is added and array size increases automatically

D. The array is converted to a slice automatically

Solution

1. Step 1: Understand Go array size

   Arrays in Go have a fixed size defined at declaration and cannot grow.

2. Step 2: Effect of insertion at end

   Since size is fixed, you cannot add new elements beyond the declared size.

3. Final Answer:

   You cannot insert because arrays have fixed size -> Option A

4. Quick Check:

   Fixed size array = no insertion beyond size [OK]

Hint: Arrays have fixed size; no automatic growth on insertion [OK]

Common Mistakes:

• Thinking arrays can grow automatically
• Confusing arrays with slices
• Assuming insertion replaces last element

2. Which of the following is the correct way to append an element 10 to a slice named nums in Go?

easy

A. nums = nums + 10

B. nums.append(10)

C. append(nums, 10)

D. nums = append(nums, 10)

Solution

1. Step 1: Recall Go slice append syntax

   In Go, append returns a new slice with the element added, so assignment is needed.

2. Step 2: Check each option

   nums = append(nums, 10) correctly assigns the result of append to nums. Others are invalid syntax or missing assignment.

3. Final Answer:

   nums = append(nums, 10) -> Option D

4. Quick Check:

   Use append with assignment to add element [OK]

Hint: Always assign append result back to slice variable [OK]

Common Mistakes:

• Not assigning append result back
• Using method call syntax like nums.append()
• Trying to add with + operator

3. What is the output of the following Go code?

nums := []int{1, 2, 3}
nums = append(nums, 4)
fmt.Println(nums)

medium

A. [1 2 3]

B. [4 1 2 3]

C. [1 2 3 4]

D. Compilation error

Solution

1. Step 1: Understand initial slice and append

   nums starts as [1 2 3]. append(nums, 4) adds 4 at the end.

2. Step 2: Print the updated slice

   After append, nums becomes [1 2 3 4], which is printed.

3. Final Answer:

   [1 2 3 4] -> Option C

4. Quick Check:

   Appending 4 adds it at end [OK]

Hint: append adds element at end, print shows updated slice [OK]

Common Mistakes:

• Expecting original slice without new element
• Thinking append adds at start
• Confusing slice with array syntax

4. Identify the error in the following Go code that tries to insert 5 at the end of an array:

arr := [3]int{1, 2, 3}
arr = append(arr, 5)
fmt.Println(arr)

medium

A. Cannot use append on array; append works only on slices

B. Array size is too small; must declare larger array

C. Missing import for fmt package

D. Syntax error in array declaration

Solution

1. Step 1: Check type of arr

   arr is declared as an array [3]int, which has fixed size and no append method.

2. Step 2: Understand append usage

   append works only on slices, not arrays. Using append on array causes error.

3. Final Answer:

   Cannot use append on array; append works only on slices -> Option A

4. Quick Check:

   append requires slice, not array [OK]

Hint: append works only on slices, not fixed-size arrays [OK]

Common Mistakes:

• Trying to append to fixed-size array
• Ignoring difference between array and slice
• Assuming append auto-converts array to slice

5. Given a slice data := []int{2, 4, 6}, which code snippet correctly inserts the value 8 at the end and then doubles all elements?

hard

A. data = append(data, 8)
for _, v := range data {
v *= 2
}
fmt.Println(data)

B. data = append(data, 8)
for i := range data {
data[i] *= 2
}
fmt.Println(data)

C. data = append(data, 8)
for i := 0; i < len(data); i++ {
data[i] = data[i] + 2
}
fmt.Println(data)

D. data = append(data, 8)
for i := range data {
data[i] = data[i] / 2
}
fmt.Println(data)

Solution

1. Step 1: Append 8 to slice

   data = append(data, 8) adds 8 at the end, making data [2 4 6 8].

2. Step 2: Double each element correctly

   Using for i := range data and data[i] *= 2 doubles each element in place.

3. Step 3: Check other options

   data = append(data, 8) for _, v := range data { v *= 2 } fmt.Println(data) doubles copy of value, not original slice. Options C and D do wrong math.

4. Final Answer:

   data = append(data, 8) for i := range data { data[i] *= 2 } fmt.Println(data) -> Option B

5. Quick Check:

   Append then modify elements by index [OK]

Hint: Modify slice elements by index, not by value copy [OK]

Common Mistakes:

• Modifying value copy in range instead of slice element
• Using wrong arithmetic operation
• Not assigning append result back