Cell array indexing (curly vs parentheses) in MATLAB - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of cell array indexing with parentheses

What is the output of the following MATLAB code?

MATLAB

C = {10, 20, 30};
result = C(2);
disp(result);

A The numeric value 20

B A 1x1 cell array containing the value 20

C An error because of wrong indexing

D A 1x3 cell array containing all elements

💡 Hint

Parentheses return a cell array subset, not the content inside.

Using parentheses () on a cell array returns a cell array containing the selected cells. So C(2) returns a 1x1 cell array with the second element inside, not the element itself.

❓ Predict Output

intermediate

Output of cell array indexing with curly braces

What is the output of this MATLAB code?

MATLAB

C = {10, 20, 30};
result = C{2};
disp(result);

A The numeric value 20

B A 1x1 cell array containing the value 20

C An error because of wrong indexing

D A 1x3 cell array containing all elements

💡 Hint

Curly braces extract the content inside the cell.

Using curly braces {} extracts the content inside the cell. So C{2} returns the numeric value 20 directly.

❓ Predict Output

advanced

Result of combining parentheses and curly braces

What is the output of this MATLAB code snippet?

MATLAB

C = {1, {2, 3}, 4};
result = C{2}(1);
disp(result);

A The numeric value 3

B A 1x1 cell array containing 2

C An error because of invalid indexing

D The numeric value 2

💡 Hint

C{2} extracts the second cell content, which is itself a cell array.

C{2} extracts {2,3}, a cell array. Then (1) indexes the first element of that cell array with parentheses, returning a 1x1 cell array containing 2.

❓ Predict Output

advanced

Output when mixing parentheses and curly braces incorrectly

What error or output does this MATLAB code produce?

MATLAB

C = {1, 2, 3};
result = C{1}(2);
disp(result);

A Index exceeds matrix dimensions error

B The numeric value 2

C A 1x1 cell array containing 2

D No error, outputs 1

💡 Hint

C{1} extracts the numeric 1, which is scalar and cannot be indexed at (2).

C{1} is the numeric value 1. Trying to index (2) on a scalar number causes an 'Index exceeds matrix dimensions' error.

🧠 Conceptual

expert

Difference between parentheses and curly braces in cell arrays

Which statement correctly describes the difference between using parentheses () and curly braces {} when indexing cell arrays in MATLAB?

A Parentheses return the content inside the cell; curly braces return a cell array containing the selected cells.

B Both parentheses and curly braces return a cell array but parentheses allow multiple indexing.

C Parentheses return a cell array containing the selected cells; curly braces return the content inside the cell.

D Both parentheses and curly braces return the content inside the cell but in different data types.

💡 Hint

Think about what type of output you get from each indexing style.

Parentheses () return a subset of the cell array as a cell array. Curly braces {} extract the actual content inside the cell.