Indexed array declaration in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an indexed array named 'fruits' with three elements.

Bash Scripting

fruits=[1]

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

A(apple banana cherry)

B[0]=apple [1]=banana [2]=cherry

C"apple" "banana" "cherry"

Dapple, banana, cherry

Attempts:

3 left

💡 Hint

Common Mistakes

Using commas between elements instead of spaces.

Using quotes around the whole list instead of individual elements.

Using key=value pairs which is for associative arrays.

In bash, indexed arrays are declared using parentheses with space-separated values, like (apple banana cherry).

2fill in blank

medium

Complete the code to print the second element of the 'colors' array.

Bash Scripting

echo ${colors[1]

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

A[2]

B[0]

C[1]

D[3]

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 2 instead of 1 for the second element.

Forgetting the square brackets around the index.

Array indices in bash start at 0, so the second element is at index 1.

3fill in blank

hard

Fix the error in the array declaration to correctly declare an indexed array named 'numbers'.

Bash Scripting

numbers=[1]

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

A(1 2 3 4 5)

B[1 2 3 4 5]

C{1,2,3,4,5}

D"1 2 3 4 5"

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets which is invalid for array declaration.

Using curly braces or quotes which create strings, not arrays.

Indexed arrays in bash are declared with parentheses and space-separated values.

4fill in blank

hard

Fill both blanks to declare an indexed array 'pets' with three elements and print the first element.

Bash Scripting

pets=[1]
echo ${pets[2]

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

A(dog cat bird)

B[0]

C[1]

D"dog cat bird"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes instead of parentheses for declaration.

Using index 1 instead of 0 to access the first element.

The array is declared with parentheses and elements separated by spaces. The first element is at index 0.

5fill in blank

hard

Fill all three blanks to declare an indexed array 'tools', add a new element, and print the last element.

Bash Scripting

tools=[1]
tools[[2]]=[3]
echo ${tools[2]}

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

A(hammer screwdriver)

B2

C"wrench"

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong indices when adding or printing elements.

Not using quotes around the new element string.

Declare the array with two elements, add a third at index 2, then print the element at index 2.

Practice

1. What is the correct way to declare an indexed array named fruits with values apple, banana, and cherry in Bash?

easy

A. fruits=[apple, banana, cherry]

B. fruits=("apple, banana, cherry")

C. fruits={apple banana cherry}

D. fruits=(apple banana cherry)

Solution

1. Step 1: Understand Bash array declaration syntax

   Bash arrays use parentheses with space-separated values, no commas or braces.

2. Step 2: Check each option's syntax

   fruits=(apple banana cherry) uses parentheses and spaces correctly. Square brackets and braces are incorrect. fruits=("apple, banana, cherry") treats all values as one string.

3. Final Answer:

   fruits=(apple banana cherry) -> Option D

4. Quick Check:

   Parentheses + spaces = correct array declaration [OK]

Hint: Use parentheses and spaces, no commas or braces [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Including commas between values
• Putting all values inside quotes as one string

2. Which of the following is the correct syntax to declare an empty indexed array named numbers in Bash?

easy

A. numbers={}

B. numbers=()

C. numbers=[]

D. numbers=""

Solution

1. Step 1: Recall empty array declaration in Bash

   An empty indexed array is declared with empty parentheses.

2. Step 2: Evaluate each option

   numbers=() uses empty parentheses correctly. Braces and square brackets are invalid. numbers="" assigns an empty string, not an array.

3. Final Answer:

   numbers=() -> Option B

4. Quick Check:

   Empty parentheses declare empty array [OK]

Hint: Empty parentheses mean empty array [OK]

Common Mistakes:

• Using square brackets or braces instead of parentheses
• Assigning empty string instead of array
• Confusing array declaration with variable assignment

3. Given the array declaration colors=(red green blue), what will be the output of echo ${colors[1]}?

medium

A. green

B. colors[1]

C. blue

D. red

Solution

1. Step 1: Understand array indexing in Bash

   Indexed arrays start at 0, so index 1 is the second element.

2. Step 2: Identify the element at index 1

   colors[0] = red, colors[1] = green, colors[2] = blue.

3. Final Answer:

   green -> Option A

4. Quick Check:

   Index 1 = second element = green [OK]

Hint: Array indexes start at zero [OK]

Common Mistakes:

• Thinking array starts at 1 instead of 0
• Printing the variable name instead of value
• Confusing index with value

4. What is wrong with this array declaration?

myarray=(one two three four five six seven eight nine ten

medium

A. Array name is invalid

B. Values should be quoted

C. Missing closing parenthesis

D. Values must be comma separated

Solution

1. Step 1: Check array syntax completeness

   The declaration starts with '(' but does not have a closing ')'.

2. Step 2: Verify other syntax rules

   Values do not need quotes if no spaces, array name is valid, commas are not used in Bash arrays.

3. Final Answer:

   Missing closing parenthesis -> Option C

4. Quick Check:

   Parentheses must open and close [OK]

Hint: Always close parentheses in array declaration [OK]

Common Mistakes:

• Forgetting the closing parenthesis
• Adding commas between values
• Quoting values unnecessarily

5. How can you declare an indexed array days with the values Mon, Tue, and Wed, then print the total number of elements in the array?

hard

A. days=(Mon Tue Wed); echo ${#days[@]}

B. days=[Mon Tue Wed]; echo ${#days}

C. days=(Mon, Tue, Wed); echo ${#days[@]}

D. days=(Mon Tue Wed); echo ${days.length}

Solution

1. Step 1: Declare the array correctly

   Use parentheses with space-separated values: days=(Mon Tue Wed).

2. Step 2: Use correct syntax to get array length

   Use ${#days[@]} to get the number of elements in the array.

3. Final Answer:

   days=(Mon Tue Wed); echo ${#days[@]} -> Option A

4. Quick Check:

   Parentheses + ${#array[@]} = count [OK]

Hint: Use ${#array[@]} to get array length [OK]

Common Mistakes:

• Using square brackets for array declaration
• Using commas between values
• Using incorrect syntax for length like ${#days} or .length