Dynamic field names in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are dynamic field names in MATLAB structures?

Dynamic field names allow you to create or access structure fields using variable names instead of fixed names. This means you can decide the field name while the program runs.

beginner

How do you assign a value to a dynamic field name in a MATLAB structure?

Use parentheses and a string variable for the field name, like this: structVar.(fieldName) = value; where fieldName is a variable holding the field name as a string.

intermediate

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

MATLAB will give an error saying the field does not exist. You can check if the field exists first using isfield(structVar, fieldName) to avoid errors.

intermediate

Example: How to create a structure with dynamic field names from a list of names?

You can loop through the list and assign values like this:<br>

names = {'age', 'height'};<br>for i = 1:length(names)<br>  s.(names{i}) = i*10;<br>end

<br>This creates fields 'age' and 'height' with values 10 and 20.

beginner

Why are dynamic field names useful in MATLAB?

They let you write flexible code that can handle different data fields without hardcoding names. This is helpful when field names come from user input or external data.

How do you access a dynamic field named stored in variable fname of structure s?

A s[fname]

B s.fname

C s{fname}

D s.(fname)

Use parentheses and dot notation with the variable holding the field name: s.(fname).

What MATLAB function checks if a dynamic field exists in a structure?

A fieldexists

B isfield

C hasfield

D checkfield

The function isfield(structure, fieldName) returns true if the field exists.

Which of these is the correct way to assign 100 to a dynamic field fname in structure s?

A s.(fname) = 100;

B s.fname = 100;

C s{fname} = 100;

D s[fname] = 100;

Use s.(fname) = 100; to assign value to a dynamic field.

What error occurs if you try to access a non-existing dynamic field without checking?

A Syntax error

B Index exceeds matrix dimensions

C Field does not exist error

D No error, returns empty

MATLAB throws a 'Field does not exist' error if you access a missing field.

Why use dynamic field names instead of fixed field names?

A To make code flexible for different field names

B To speed up code execution

C To hardcode field names

D To avoid using structures

Dynamic field names let you write flexible code that adapts to different field names.

Explain how to create and access dynamic field names in a MATLAB structure.

Think about how you use variables to name fields.

Describe a situation where dynamic field names are helpful in MATLAB programming.

Consider working with data that changes structure.