Structures and field access in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a structure in MATLAB?

A structure in MATLAB is a data type that groups related data using named fields, allowing you to organize different types of data together like a real-world object.

beginner

How do you create a structure with fields 'Name' and 'Age' in MATLAB?

You can create it like this: <br> person.Name = 'Alice';<br>person.Age = 30;

beginner

How do you access the field 'Age' from a structure variable 'person'?

Use dot notation: <br> person.Age returns the value stored in the 'Age' field.

intermediate

How can you check if a field exists in a structure?

Use the function isfield(structure, 'fieldname'). It returns true if the field exists, false otherwise.

intermediate

What happens if you try to access a field that does not exist in a MATLAB structure?

MATLAB gives an error saying the field does not exist. You should check with isfield before accessing to avoid this.

How do you add a new field 'Height' with value 170 to an existing structure 'person'?

A person.Height = 170;

B addfield(person, 'Height', 170);

C person('Height') = 170;

D person->Height = 170;

In MATLAB, you add or modify fields using dot notation like person.Height = 170;.

Which function checks if a field exists in a structure?

A fieldexists()

B hasfield()

C isfield()

D checkfield()

The correct function is isfield(structure, 'fieldname').

What is the output of person.Name if person.Name = 'Bob';?

A Name

B Error

C person.Name

D 'Bob'

Accessing person.Name returns the string stored in that field, here 'Bob'.

How do you create an empty structure with fields 'X' and 'Y'?

A struct(X, Y)

B struct('X', [], 'Y', [])

C emptystruct('X', 'Y')

D newstruct('X', 'Y')

Use struct('X', [], 'Y', []) to create a structure with empty fields.

What happens if you try to access person.Weight but 'Weight' is not a field?

A Throws an error

B Returns empty

C Returns zero

D Creates the field automatically

MATLAB throws an error if you access a non-existent field.

Explain how to create a MATLAB structure and access its fields.

Think about how you name fields and get their values.

Describe how to safely check if a field exists before accessing it in a structure.

Use a function that returns true or false for field presence.