String vs character array in MATLAB - Quick Revision & Key Differences

Recall & Review

beginner

What is a string in MATLAB?

A string in MATLAB is a sequence of characters enclosed in double quotes, used to represent text data easily and support many text operations.

beginner

What is a character array in MATLAB?

A character array is a sequence of characters enclosed in single quotes, stored as an array of characters, often used before strings were introduced.

beginner

How do you create a string and a character array in MATLAB?

String: s = "Hello"; Character array: c = 'Hello';

intermediate

Can you concatenate strings and character arrays the same way in MATLAB?

No. Strings use the + operator or functions like strcat, while character arrays use square brackets [].

intermediate

Why might you choose a string over a character array in MATLAB?

Strings are easier to work with for text processing, support many built-in functions, and handle Unicode better than character arrays.

How do you define a string in MATLAB?

A Using curly braces, e.g., {Hello}

B Using single quotes, e.g., 'Hello'

C Using double quotes, e.g., "Hello"

D Using parentheses, e.g., (Hello)

Strings in MATLAB are created with double quotes, like "Hello".

Which data type uses single quotes in MATLAB?

A String

B Character array

C Numeric array

D Cell array

Character arrays use single quotes, like 'Hello'.

What operator is used to concatenate two strings in MATLAB?

A -

B []

C *

D +

Strings are concatenated with the + operator or functions like strcat.

How do you concatenate two character arrays in MATLAB?

A []

B +

C strcat() only

D append()

Character arrays are concatenated using square brackets [].

Which is true about strings compared to character arrays in MATLAB?

A Strings support Unicode better

B Character arrays support Unicode better

C Both support Unicode equally

D Neither supports Unicode

Strings support Unicode better than character arrays.

Explain the difference between a string and a character array in MATLAB.

Think about how you write text and what functions you can use.

Describe how to concatenate strings and character arrays in MATLAB and why they differ.

Consider the data type and operator used.

Practice

1. Which of the following correctly represents a string in MATLAB?

easy

A. 'Hello World'

B. ('Hello World')

C. {'Hello World'}

D. "Hello World"

Solution

1. Step 1: Understand string syntax in MATLAB

   Strings in MATLAB are enclosed in single quotes, like 'Hello World'.

2. Step 2: Identify string and character array syntax

   In MATLAB, single quotes denote character arrays (which are often used as strings). Double quotes denote string arrays introduced in newer MATLAB versions, but the classic string representation is single quotes.

3. Final Answer:

   'Hello World' -> Option A

4. Quick Check:

   Single quotes denote character arrays (strings) = B [OK]

Hint: Strings use single quotes in MATLAB [OK]

Common Mistakes:

• Confusing single quotes for strings
• Using curly braces which create cell arrays
• Using parentheses which are invalid for strings

2. Which of the following is the correct way to create a character array in MATLAB?

easy

A. charArray = "abc";

B. charArray = ["a", "b", "c"];

C. charArray = { 'a', 'b', 'c' };

D. charArray = 'abc';

Solution

1. Step 1: Recognize character array syntax

   Character arrays are created using single quotes around text, like 'abc'.

2. Step 2: Differentiate from string and cell array

   Double quotes create string arrays, and curly braces create cell arrays, so only single quotes create character arrays.

3. Final Answer:

   charArray = 'abc'; -> Option D

4. Quick Check:

   Character arrays use single quotes = C [OK]

Hint: Use single quotes for character arrays, double for strings [OK]

Common Mistakes:

• Using double quotes for character arrays
• Using curly braces which create cell arrays
• Using square brackets with commas incorrectly

3. What is the output of the following MATLAB code?

str = "MATLAB";
charArr = 'MATLAB';
disp(class(str));
disp(class(charArr));

medium

A. string
char

B. char
string

C. string
string

D. char
char

Solution

1. Step 1: Identify variable types

   Variable str is created with double quotes, so it is a string type. Variable charArr uses single quotes, so it is a character array (char).

2. Step 2: Understand class() output

   The class() function returns the type name as a string. So class(str) returns 'string' and class(charArr) returns 'char'.

3. Final Answer:

   string char -> Option A

4. Quick Check:

   Double quotes = string, single quotes = char [OK]

Hint: class() shows 'string' for double quotes, 'char' for single quotes [OK]

Common Mistakes:

• Assuming both are 'char' type
• Confusing output order
• Thinking class() returns variable content

4. Consider this MATLAB code snippet:

str = 'Hello';
str(1) = "h";

What is the error in this code?

medium

A. Indexing starts at 0, so str(1) is invalid

B. Cannot assign double quotes to a character array element

C. Strings cannot be indexed like arrays

D. No error, code runs fine

Solution

1. Step 1: Identify variable type

   Variable str is created with single quotes, so it is a character array.

2. Step 2: Understand assignment rules for character arrays

   Character array elements must be assigned single characters using single quotes. Assigning a double-quoted string "h" causes a type mismatch error.

3. Final Answer:

   Cannot assign double quotes to a character array element -> Option B

4. Quick Check:

   Character arrays need single quotes for elements [OK]

Hint: Assign single characters with single quotes to char arrays [OK]

Common Mistakes:

• Using double quotes to assign char array elements
• Thinking MATLAB indexing starts at 0
• Assuming strings can't be indexed

5. You want to concatenate the words "Data" and 'Science' in MATLAB to form a string. Which code correctly does this and results in a string type?

hard

A. result = "Data" + 'Science';

B. result = "Data" + "Science";

C. result = "Data" + string('Science');

D. result = "Data" + char('Science');

Solution

1. Step 1: Understand types of inputs

   "Data" is a string. 'Science' is a character array. To concatenate strings, both must be string type.

2. Step 2: Convert character array to string before concatenation

   Using string('Science') converts the char array to string, allowing + operator to concatenate strings properly.

3. Final Answer:

   result = "Data" + string('Science'); -> Option C

4. Quick Check:

   Convert char to string before + concatenation [OK]

Hint: Convert char arrays to strings before using + for concatenation [OK]

Common Mistakes:

• Trying to add string and char directly
• Using + with char arrays (causes error)
• Not converting char to string before concatenation