Cell array indexing (curly vs parentheses) in MATLAB - Quick Revision & Key Differences

Recall & Review

beginner

What does using parentheses () do when indexing a cell array in MATLAB?

Parentheses () return a subset of the cell array as another cell array, preserving the cell structure.

beginner

What does using curly braces {} do when indexing a cell array in MATLAB?

Curly braces {} extract the contents inside the cell, returning the actual data stored in that cell.

beginner

Given a cell array C = {1, 'hello', [2 3]}, what is the result of C(2)?

C(2) returns a 1x1 cell array containing the string 'hello'.

beginner

Given the same cell array C = {1, 'hello', [2 3]}, what is the result of C{2}?

C{2} returns the string 'hello' directly, not inside a cell.

intermediate

Why would you use parentheses () instead of curly braces {} when indexing a cell array?

Use parentheses () when you want to keep the result as a cell array, for example, to pass a subset of cells to another function expecting cells.

What type of output do you get when you use curly braces {} to index a cell array?

A A cell array containing the cell

B An error

C A numeric array

D The contents inside the cell

Curly braces {} extract the actual contents inside the cell.

What does C(1:2) return if C is a cell array?

A A cell array containing the first two cells

B The contents of the first two cells concatenated

C The contents of the first cell only

D An error

Parentheses () return a subset of the cell array as a cell array.

If C = {10, 20, 30}, what does C{3} return?

A [30]

B {30}

C 30

D A cell array with 30

Curly braces {} return the content inside the cell, here the number 30.

Which indexing method would you use to get a cell array containing only the second cell of C?

A C.2

B C(2)

C C[2]

D C{2}

Parentheses () return a cell array subset, so C(2) returns a cell array with the second cell.

What happens if you try to assign a value to C{2} when C is a cell array?

A The content inside the second cell is replaced

B The second cell is replaced with a new cell

C An error occurs

D The entire cell array is replaced

Using curly braces {} on the left side replaces the content inside that cell.

Explain the difference between using parentheses () and curly braces {} when indexing a cell array in MATLAB.

Think about whether you want the cell itself or what is inside it.

Describe a situation where you would prefer to use parentheses () over curly braces {} when working with cell arrays.

Consider when the output needs to remain a cell array.