String concatenation in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to concatenate two strings using the correct operator.

MATLAB

result = [str1 [1] str2];

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

A+

Bstrcat

C.*

D[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using + operator for string concatenation

Using .* which is for element-wise multiplication

In MATLAB, square brackets [] are used to concatenate strings horizontally.

2fill in blank

medium

Complete the code to concatenate strings with a space between them.

MATLAB

result = [str1 [1] str2];

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

A' '

B+

C,

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using comma or semicolon which do not concatenate strings

Using plus sign which is invalid for strings

To add a space between two strings in MATLAB, include a space character inside single quotes.

3fill in blank

hard

Fix the error in the code to concatenate strings correctly.

MATLAB

result = strcat(str1, [1], str2);

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

A,

B' '

C+

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using comma or semicolon which are not valid string arguments

Using plus sign which is invalid in this context

The strcat function concatenates strings. To add a space between them, pass a space character as a string.

4fill in blank

hard

Fill both blanks to create a string array concatenating str1 and str2 with a space.

MATLAB

result = [[1] [2] str2];

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

Astr1

B' '

C+

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using + operator which is invalid for string concatenation in MATLAB

Using semicolon which separates rows, not concatenates horizontally

Use square brackets to concatenate str1 and str2 with a space character in between.

5fill in blank

hard

Fill all three blanks to concatenate str1, a comma, and str2.

MATLAB

result = [[1] [2] [3]];

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

Astr1

B','

C' '

Dstr2

Attempts:

3 left

💡 Hint

Common Mistakes

Using plus signs for concatenation

Forgetting to put the comma in quotes

Concatenate str1, a comma character, and str2 using square brackets.

Practice

1. Which of the following is the correct way to concatenate two strings 'Hello' and 'World' in MATLAB?

easy

A. ['Hello' 'World']

B. 'Hello' + 'World'

C. concat('Hello', 'World')

D. 'Hello' & 'World'

Solution

1. Step 1: Understand MATLAB string concatenation syntax

   In MATLAB, square brackets [ ] are used to join strings or character arrays.

2. Step 2: Apply concatenation to given strings

   Using ['Hello' 'World'] joins the two strings into 'HelloWorld'. Other options use incorrect syntax.

3. Final Answer:

   ['Hello' 'World'] -> Option A

4. Quick Check:

   Use [ ] to join strings in MATLAB [OK]

Hint: Use square brackets [ ] to join strings in MATLAB [OK]

Common Mistakes:

• Using + operator for strings
• Using functions not defined in MATLAB
• Using & operator which is invalid for strings

2. Which of the following MATLAB statements correctly concatenates the strings 'Data' and '123'?

easy

A. str = 'Data' + '123';

B. str = strcat('Data', 123);

C. str = ['Data' '123'];

D. str = 'Data' & '123';

Solution

1. Step 1: Check syntax for string concatenation

   In MATLAB, concatenation uses square brackets [ ] for character arrays or strings.

2. Step 2: Evaluate each option

   str = ['Data' '123']; uses ['Data' '123'] which correctly joins the two strings. str = 'Data' + '123'; uses + which is invalid. str = strcat('Data', 123); uses strcat but passes a number without converting it to string. str = 'Data' & '123'; uses & which is invalid.

3. Final Answer:

   str = ['Data' '123']; -> Option C

4. Quick Check:

   Concatenate strings with [ ] brackets [OK]

Hint: Use [ ] brackets to join strings, not + or & [OK]

Common Mistakes:

• Using + operator for strings
• Passing numbers directly to strcat without conversion
• Using & operator for concatenation

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

str1 = 'Good';
str2 = 'Morning';
result = [str1 ' ' str2];
disp(result);

medium

A. Good Morning

B. GoodMorning

C. Good_Morning

D. Error

Solution

1. Step 1: Analyze the concatenation expression

   The code concatenates str1, a space character ' ', and str2 using square brackets.

2. Step 2: Understand the output of disp

   The result is 'Good Morning' with a space between the words, so disp prints it exactly as 'Good Morning'.

3. Final Answer:

   Good Morning -> Option A

4. Quick Check:

   Concatenate with space inside [ ] to separate words [OK]

Hint: Add ' ' inside [ ] to insert space between strings [OK]

Common Mistakes:

• Forgetting to add space character
• Using + operator instead of [ ]
• Expecting underscore instead of space

4. The following MATLAB code is intended to concatenate 'Hi' and 'There' but causes an error. What is the error and how to fix it?

str1 = 'Hi';
str2 = 'There';
result = str1 + str2;
disp(result);

medium

A. No error, output is 'HiThere'

B. Error: Use strcat function instead of +

C. Error: Use & operator instead of +

D. Error: Use square brackets [ ] instead of + for concatenation

Solution

1. Step 1: Identify the cause of error

   Using + operator between strings in MATLAB causes an error because + is not defined for character arrays.

2. Step 2: Correct the concatenation method

   Replace + with square brackets [ ] to join strings: result = [str1 str2];

3. Final Answer:

   Error: Use square brackets [ ] instead of + for concatenation -> Option D

4. Quick Check:

   Concatenate strings with [ ], not + [OK]

Hint: Replace + with [ ] to fix string concatenation error [OK]

Common Mistakes:

• Using + operator for strings
• Trying to use & operator
• Assuming strcat always fixes + errors

5. You want to create a message in MATLAB that says 'User: John, Age: 30' by concatenating variables name = 'John' and age = 30. Which code correctly creates this message?

hard

A. msg = ['User: ' + name + ', Age: ' + string(age)];

B. msg = ['User: ' name ', Age: ' num2str(age)];

C. msg = strcat('User: ', name, ', Age: ', age);

D. msg = ['User: ' name ', Age: ' age];

Solution

1. Step 1: Understand variable types and concatenation

   name is a string, age is a number. To concatenate, age must be converted to string using num2str.

2. Step 2: Check each option for correctness

   msg = ['User: ' name ', Age: ' num2str(age)]; uses [ ] and num2str(age) correctly. msg = ['User: ' name ', Age: ' age]; tries to concatenate number directly causing error. msg = strcat('User: ', name, ', Age: ', age); uses strcat but passes number without conversion. msg = ['User: ' + name + ', Age: ' + string(age)]; uses + operator which is invalid.

3. Final Answer:

   msg = ['User: ' name ', Age: ' num2str(age)]; -> Option B

4. Quick Check:

   Convert numbers to strings before concatenation [OK]

Hint: Convert numbers to strings with num2str before concatenation [OK]

Common Mistakes:

• Concatenating numbers without conversion
• Using + operator for strings
• Passing numbers directly to strcat