Accessing array elements in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

How do you define an array in Bash?

You define an array by listing elements inside parentheses, separated by spaces. For example: my_array=(apple banana cherry)

beginner

How do you access the first element of an array named my_array in Bash?

Use the syntax ${my_array[0]} to get the first element because array indexes start at 0.

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What does ${my_array[@]} do in Bash?

It expands to all elements of the array my_array. Useful to loop over or print all items.

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How can you get the number of elements in a Bash array my_array?

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

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What happens if you try to access an array element with an index that does not exist?

You get an empty string because the element is not set. Bash does not throw an error for out-of-range indexes.

In Bash, how do you access the third element of an array named fruits?

A ${fruits(3)}

B ${fruits[2]}

C ${fruits[3]}

D ${fruits[1]}

Array indexes start at 0, so the third element is at index 2.

What does ${my_array[@]} return in Bash?

A All elements of the array

B The first element only

C The length of the array

D The last element only

The @ symbol expands to all elements in the array.

How do you find the number of elements in a Bash array colors?

A ${colors.size}

B ${colors.length}

C length(colors)

D ${#colors[@]}

The syntax ${#array[@]} returns the count of elements.

What will happen if you access ${my_array[10]} but the array has only 3 elements?

A Returns the last element

B Throws an error

C Returns an empty string

D Returns null

Bash returns an empty string for out-of-range indexes without error.

Which of these is the correct way to define an array in Bash?

A my_array=(one two three)

B my_array=[one, two, three]

C my_array={one two three}

D my_array: one, two, three

Arrays are defined with parentheses and space-separated elements.

Explain how to access elements in a Bash array and how indexing works.

Think about how you pick items from a list starting at zero.

Describe how to get all elements and the length of a Bash array.

Consider how you might count or list all items in a shopping list.