Text Files in MATLAB

📄 Text Files in MATLAB

MATLAB provides high-level and low-level functions to read from and write to text files efficiently.
MATLAB is developed by MathWorks.

🔹 What Is a Text File?

A text file stores data in plain text format, such as:

• Numbers

• Characters

• Words

• Lines of text

Example:

1️⃣ Reading Numeric Text Files — load()

Used when the text file contains only numeric data.

🔸 Example (data.txt)

🔸 MATLAB Code

Output

📌 Works only for numeric data.

2️⃣ Reading Text Files — fopen() + fscanf()

Used for formatted numeric data.

Output

3️⃣ Reading Line-by-Line — fgets()

Best for text content.

🔸 Example (info.txt)

🔸 MATLAB Code

Output

4️⃣ Reading Entire File — fileread()

Reads the whole text file at once.

📌 Simple and fast for small files.

5️⃣ Writing to a Text File — fprintf()

Output (report.txt)

6️⃣ Appending Data to a Text File

📌 'a' mode adds data without deleting existing content.

7️⃣ Writing Multiple Lines

8️⃣ Closing Files Properly

📌 Always close files to avoid memory leaks.

⚠️ Important Notes

• 'r' → read mode

• 'w' → write (overwrites file)

• 'a' → append

• Always check file ID:

🎯 Interview Questions: Text Files in MATLAB

🔹 Q1. Which function opens a text file?

Answer: fopen()

🔹 Q2. Which function reads formatted data?

Answer: fscanf()

🔹 Q3. How do you read a full text file at once?

Answer: fileread()

🔹 Q4. Which function writes formatted text?

Answer: fprintf()

🔹 Q5. Difference between fgets() and fscanf()?

Answer:
fgets() → reads one line as text
fscanf() → reads formatted data

🔹 Q6. Why is fclose() important?

Answer:
To release file resources and avoid data corruption.

✅ Summary

• Text files store plain data

• MATLAB supports low-level file handling

• fopen, fscanf, fgets, fprintf are key functions

• Essential for logs, reports & custom data formats