File path handling in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to join folder and file name into a full path.

MATLAB

fullPath = fullfile([1], 'data.txt');

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

AfolderName

BfileName

CpathName

DfilePath

Attempts:

3 left

💡 Hint

Common Mistakes

Using the file name variable instead of the folder name.

Using a variable that does not exist.

The fullfile function joins folder and file names into a full path. Here, folderName is the folder part.

2fill in blank

medium

Complete the code to extract the file extension from a file path.

MATLAB

[~, ~, [1]] = fileparts(filePath);

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

Aextension

Bfolder

Cfilename

Dfilepath

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong output position for the extension.

Confusing file name with extension.

The fileparts function returns the folder, file name, and extension. The third output is the file extension.

3fill in blank

hard

Fix the error in the code to check if a path is a folder.

MATLAB

if isfolder([1])
    disp('It is a folder.');
end

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

AfilePath

BfolderPath

CfileName

DfileExtension

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a file name or extension instead of a folder path.

Using a variable that does not represent a folder.

The isfolder function checks if the input is a folder path. Use the variable that stores the folder path.

4fill in blank

hard

Fill both blanks to create a path and check if it exists.

MATLAB

fullPath = fullfile([1], [2]);
if exist(fullPath, 'file')
    disp('File exists.');
end

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

AfolderName

BfileName

CfolderPath

DfileExtension

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping folder and file name in fullfile.

Using file extension instead of file name.

Use folderName and fileName to build the full path. Then exist checks if the file exists.

5fill in blank

hard

Fill all three blanks to split a path and rebuild it with a new extension.

MATLAB

[folder, name, [1]] = fileparts(oldPath);
newPath = fullfile(folder, [name [2] [3]]);

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

Aextension

B'.'

C'txt'

D'/'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names for extension.

Using slash '/' instead of dot '.' for extension separator.

Extract the extension with extension. Then rebuild the file name by joining name, a dot '.', and the new extension 'txt'.

Practice

1. What does the MATLAB function fullfile do?

easy

A. Joins folder and file names into a full file path safely

B. Splits a full file path into folder, name, and extension

C. Reads the contents of a file

D. Deletes a file from the disk

Solution

1. Step 1: Understand the purpose of fullfile

   fullfile is used to combine folder and file names into one complete path, handling different operating systems correctly.

2. Step 2: Compare with other functions

   fileparts splits paths, reading or deleting files are unrelated to fullfile.

3. Final Answer:

   Joins folder and file names into a full file path safely -> Option A

4. Quick Check:

   fullfile joins paths [OK]

Hint: Remember: fullfile combines parts into one path [OK]

Common Mistakes:

• Confusing fullfile with fileparts
• Thinking fullfile reads or deletes files
• Assuming fullfile only works on Windows

2. Which of the following is the correct syntax to split a full file path into folder, name, and extension in MATLAB?

easy

A. [folder, name, ext] = fileparts(path);

B. [folder, name, ext] = splitfile(path);

C. split(path, folder, name, ext);

D. fileparts = [folder, name, ext](path);

Solution

1. Step 1: Recall the correct function name and syntax

   The MATLAB function to split a path is fileparts, and it returns folder, name, and extension as outputs.

2. Step 2: Check the syntax format

   The correct syntax uses square brackets for multiple outputs: [folder, name, ext] = fileparts(path);

3. Final Answer:

   [folder, name, ext] = fileparts(path); -> Option A

4. Quick Check:

   fileparts splits path correctly [OK]

Hint: Use square brackets and fileparts to split paths [OK]

Common Mistakes:

• Using wrong function name like splitfile
• Incorrect output assignment syntax
• Trying to call fileparts like a variable

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

fullPath = fullfile('C:', 'Users', 'Documents', 'file.txt');
[folder, name, ext] = fileparts(fullPath);
disp(folder)

medium

A. file.txt

B. C:\Users\Documents

C. C:/Users/Documents/file.txt

D. Documents

Solution

1. Step 1: Understand fullfile output

   fullfile joins parts into a full path: 'C:\Users\Documents\file.txt' (Windows style).

2. Step 2: Use fileparts to split the path

   fileparts splits into folder = 'C:\Users\Documents', name = 'file', ext = '.txt'.

3. Final Answer:

   C:\Users\Documents -> Option B

4. Quick Check:

   fileparts folder output = C:\Users\Documents [OK]

Hint: fileparts(folder) excludes file name and extension [OK]

Common Mistakes:

• Expecting file name or extension as folder output
• Confusing path separators (\ vs /)
• Thinking fullfile returns a list instead of string

4. Identify the error in this MATLAB code snippet:

path = fullfile('folder', 'subfolder', 'file.txt');
[folder, name, ext] = fileparts(path);
disp(name)

medium

A. The fullfile function cannot join more than two parts

B. The function fileparts requires three output variables, not one

C. There is no error; the code runs correctly and displays 'file'

D. Variable path is a reserved word and should not be used

Solution

1. Step 1: Check variable naming

   Although path is a common variable name, it is not reserved in MATLAB and can be used safely.

2. Step 2: Verify function usage

   fileparts can return multiple outputs, but it also works correctly with three outputs as shown. fullfile can join multiple parts, more than two.

3. Final Answer:

   There is no error; the code runs correctly and displays 'file' -> Option C

4. Quick Check:

   Code runs and shows file name [OK]

Hint: Check if code runs before assuming errors [OK]

Common Mistakes:

• Thinking path is a reserved keyword
• Believing fullfile only joins two parts
• Assuming fileparts needs different syntax

5. You want to create a MATLAB script that saves a file named data.csv inside a folder results located in the current working directory. Which code snippet correctly creates the full path to save the file, regardless of the operating system?

hard

A. savePath = ['results' filesep 'data.csv'];

B. savePath = strcat('results\', 'data.csv');

C. savePath = 'results/data.csv';

D. savePath = fullfile(pwd, 'results', 'data.csv');

Solution

1. Step 1: Understand the need for OS-independent path

   Using fullfile with pwd (current folder) ensures the path works on Windows, Mac, or Linux.

2. Step 2: Analyze each option

   savePath = ['results' filesep 'data.csv']; uses filesep but misses pwd so path is relative; savePath = 'results/data.csv'; uses forward slash which may fail on Windows; savePath = strcat('results\', 'data.csv'); uses backslash manually which is error-prone.

3. Final Answer:

   savePath = fullfile(pwd, 'results', 'data.csv'); -> Option D

4. Quick Check:

   fullfile + pwd = OS-independent full path [OK]

Hint: Use fullfile with pwd for safe full paths [OK]

Common Mistakes:

• Hardcoding slashes instead of using fullfile
• Not including current directory with pwd
• Using strcat which ignores path separators