C Read Files

📘 C Read Files Tutorial

In C Read Files, file reading is done using the standard I/O library <stdio.h>.
C supports text files and binary files.

1️⃣ Basic File Reading Steps in C

1. Declare a file pointer

2. Open file using fopen()

3. Read data from file

4. Close file using fclose()

2️⃣ File Pointer Declaration

FILE is a structure defined in <stdio.h>.

3️⃣ Opening a File for Reading

File Open Modes for Reading

⚠️ If file does not exist → NULL is returned

4️⃣ Reading File Using fgetc() (Character by Character)

📌 Best for small files

5️⃣ Reading File Using fgets() (Line by Line)

✔ Reads one full line at a time
✔ Very commonly used

6️⃣ Reading File Using fscanf() (Formatted Data)

📌 Use when file has structured data

7️⃣ Reading Binary File Using fread() 🔥

✔ Used in binary files, embedded systems

8️⃣ Read Entire File (Best Interview Example ⭐)

9️⃣ Common Errors & Solutions

1.  Forgetting to close file
2.  Always use fclose(fp);
3. Not checking NULL
4. Always check file pointer
5.  Using wrong mode
6. "r" for text, "rb" for binary

🔟 Interview Questions (Very Important)

1. What is FILE in C?

2. Difference between fgetc() and fgets()

3. Difference between fscanf() and fgets()

4. What is EOF?

5. Difference between text and binary files

6. Why fread() is faster?

🔥 Real-Life Use Cases

• Reading configuration files

• Log file analysis

• Database file parsing

• Embedded systems

• OS & compiler development

✅ Summary

✔ C supports powerful file reading functions
✔ Use correct function based on file type
✔ Always check for errors
✔ Very important for placements & interviews