File path handling in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this MATLAB code using fullfile?

Consider the following MATLAB code that constructs a file path. What will be the output printed?

MATLAB

folder = 'data';
file = 'results.txt';
filepath = fullfile(folder, file);
disp(filepath);

A 'data/results.txt\'

B 'data\\results.txt'

C 'data\results.txt'

D 'data/results.txt'

💡 Hint

fullfile joins parts of a path using the correct file separator for your system.

The fullfile function joins folder and file using the system's file separator. On Windows, it uses '\' so the output is 'data\results.txt'.

❓ Predict Output

intermediate

What does fileparts return for this path?

Given the MATLAB code below, what are the outputs of [folder, name, ext]?

MATLAB

[folder, name, ext] = fileparts('C:\Users\user\Documents\report.pdf');
fprintf('%s|%s|%s', folder, name, ext);

A 'C:/Users/user/Documents|report|pdf'

B 'C:\Users\user\Documents|report|.pdf'

C 'C:\Users\user\Documents\report|pdf|'

D 'C:\Users\user\Documents|report.pdf|'

💡 Hint

fileparts splits the path into folder, filename without extension, and extension.

fileparts returns the folder path, the file name without extension, and the extension including the dot. So folder is 'C:\Users\user\Documents', name is 'report', ext is '.pdf'.

🔧 Debug

advanced

Why does this code fail to create a valid path?

This MATLAB code tries to create a file path but produces an error. What is the cause?

MATLAB

folder = 'C:\Data';
file = 'output.txt';
filepath = [folder '\' file];
disp(filepath);

A The backslash is not escaped properly, causing an invalid path string.

B The concatenation operator [] cannot be used for strings in MATLAB.

C The disp function cannot display file paths with backslashes.

D The variable 'file' is a reserved keyword and cannot be used.

💡 Hint

Check how backslashes are used in strings in MATLAB.

In MATLAB, backslash is an escape character. To include a literal backslash, you must use two backslashes \\. The code uses a single backslash '\' which is invalid.

❓ Predict Output

advanced

What is the output of this code using filesep?

What will this MATLAB code display?

MATLAB

folder = 'myfolder';
file = 'data.csv';
filepath = [folder filesep file];
disp(filepath);

A 'myfolder\data.csv'

B 'myfolder\\data.csv'

C 'myfolder/data.csv'

D 'myfolderdata.csv'

💡 Hint

filesep returns the system-specific file separator character.

filesep returns '\' on Windows and '/' on Unix. On Windows, the output is 'myfolder\data.csv'.

🧠 Conceptual

expert

How many parts does fileparts return for a UNC path?

In MATLAB, when using fileparts on a UNC path like \\server\share\folder\file.txt, how many output parts does fileparts return?

A One part: the full path as a single string

B Four parts: server, share, folder, and file

C Two parts: path and filename

D Three parts: folder, name, and extension

💡 Hint

fileparts always returns three outputs regardless of path type.

fileparts returns three outputs: folder path, file name without extension, and extension. UNC paths are treated like normal paths.

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