Cell array creation in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this cell array creation code?

Consider the following MATLAB code that creates a cell array. What will be the content of C after running it?

MATLAB

C = {1, 'text', [2 3 4]; true, {5,6}, pi};
disp(C);

A A 2x3 cell array where C{1,1} is the string '1' and C{2,2} is the number 6

B A 3x2 cell array with numbers and strings mixed incorrectly causing an error

C A numeric matrix with elements 1, 'text', [2 3 4], true, {5,6}, pi

D A 2x3 cell array where C{1,2} is the string 'text' and C{2,3} is the number pi

💡 Hint

Remember that curly braces {} create cell arrays and each element can hold different types.

The code creates a 2-by-3 cell array. Each cell can hold different data types. For example, C{1,2} holds the string 'text', and C{2,3} holds the value of pi.

❓ Predict Output

intermediate

What is the size of the cell array created here?

What is the size of the cell array C after executing this code?

C = cell(3,2);

MATLAB

C = cell(3,2);
sizeC = size(C);

A [3 2]

B [2 3]

C [1 6]

D [6 1]

💡 Hint

The cell function creates a cell array with the given number of rows and columns.

The cell(3,2) command creates a cell array with 3 rows and 2 columns, so its size is [3 2].

🔧 Debug

advanced

Identify the error in this cell array creation

This code is intended to create a 1x3 cell array with different types of elements. What error will MATLAB show when running it?

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

MATLAB

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

A Error: Dimensions of arrays being concatenated are not consistent.

B No error, creates a 2x3 cell array with missing elements filled with empty cells.

C Error: Cell arrays cannot contain numeric values.

D Error: Missing semicolon at the end of the line.

💡 Hint

Check the number of elements in each row when creating a cell array with multiple rows.

The first row has 3 elements, but the second row has only 2. MATLAB requires all rows to have the same number of elements when creating arrays, so it throws a dimension mismatch error.

🧠 Conceptual

advanced

Which option correctly creates a nested cell array?

You want to create a cell array C where the second element is itself a cell array containing numbers 10 and 20. Which code does this correctly?

A C = {5; {10, 20}; 'hello'};

B C = {5, [10, 20], 'hello'};

C C = {5, {10, 20}, 'hello'};

D C = {5, {10; 20}, 'hello'};

💡 Hint

Use curly braces inside the cell array to create nested cells.

Option C creates a 1x3 cell array where the second element is a 1x2 cell array containing 10 and 20. Option C uses a numeric array, not a cell. Option C creates a 3x1 cell array (column), not 1x3. Option C creates a nested cell with a column cell array inside, which is valid but changes the shape.

❓ Predict Output

expert

What is the output of this complex cell array indexing?

Given the cell array C = {1, {2, 3}, 4};, what is the output of disp(C{2}{1})?

MATLAB

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

A 3

B 2

C {2, 3}

D Error: Cell contents reference from a non-cell array object.

💡 Hint

Remember that C{2} accesses the second cell content, which is itself a cell array, then {1} accesses its first element.

C{2} is the cell array {2, 3}. Then C{2}{1} accesses the first element inside that nested cell, which is the number 2.