String vs character array in MATLAB - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a string variable.

MATLAB

str = [1]('Hello');

Drag options to blanks, or click blank then click option'

Astring

Bchar

Ccell

Darray

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'char' instead of 'string' creates a character array, not a string array.

In MATLAB, string creates a string array, which is different from a character array.

2fill in blank

medium

Complete the code to create a character array.

MATLAB

charArray = [1]('Hello');

Drag options to blanks, or click blank then click option'

Acellstr

Bstring

Carrayfun

Dchar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'string' creates a string array, not a character array.

The char function creates a character array in MATLAB.

3fill in blank

hard

Fix the error in the code to concatenate two strings properly.

MATLAB

result = [1] + " World";

Drag options to blanks, or click blank then click option'

A'Hello'

B"Hello"

Cstring('Hello')

Dchar('Hello')

Attempts:

3 left

💡 Hint

Common Mistakes

Using character arrays with + causes an error.

In MATLAB, string concatenation with + works only with string arrays, not character arrays.

4fill in blank

hard

Fill both blanks to create a character array and concatenate it with another.

MATLAB

a = [1]('Hi'); b = [2](' there'); result = [a b];

Drag options to blanks, or click blank then click option'

Achar

Bstring

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing string and character arrays causes errors or unexpected results.

Character arrays are created with char and concatenated using square brackets [].

5fill in blank

hard

Fill all three blanks to create a string array, convert it to character array, and get its length.

MATLAB

str = [1]({'cat', 'dog'}); charArr = [2](str(1)); len = [3](charArr);

Drag options to blanks, or click blank then click option'

Astring

Bchar

Clength

Dcellstr

Attempts:

3 left

💡 Hint

Common Mistakes

Using cellstr instead of string creates cell arrays, not string arrays.

First create a string array with string, then convert the first element to a character array with char, and finally get its length with length.

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