(435) C_120 File Handling in C - part 2 | File Pointer and fopen() function

Introduction to File Handling in C

• Importance of file handling in C programming.

• Key elements covered in previous discussions:

  • Why files are necessary.

  • Definition of a file.

  • Overview of file handling concepts.

Key Terminology in File Handling

• Familiarity with terminology is crucial for writing file handling programs.

• Essential functions and pointers used in file handling:

  • File pointer: Required to perform operations on files.

File Handling Essentials

Why Use Files?

• RAM vs. Hard Disk:

  • RAM is volatile memory; temporary data storage.

  • Hard disk is non-volatile; used for permanent data storage.

• Definition of a file:

  • Sequence of bytes that stores data permanently.

Common File Operations

• Basic operations you can perform on a file:

  • Create a file.

  • Open a file.

  • Read data from a file.

  • Write or append data to a file.

The Role of File Pointers

Understanding File Pointers

• Definition of a file pointer:

  • A pointer specifically designed to access a file in C.

  • Declared as FILE *fp; depending on the need.

Memory and Access:

• The pointer points to a file structure requiring information about the file.

• Actual process involves buffering and loading file data into RAM.

File Data Type and Initialization

Using the FILE Data Type

• Defined in stdio.h for file handling in C:

  • Includes necessary functions for file operations.

• To utilize it, include <stdio.h> in your program.

Opening a File with fopen

The fopen Function

• Used to open a file and return a file pointer.

• Syntax:

  • FILE *fopen(const char *filename, const char *mode);

• Arguments needed:

  • filename: The name of the file to open (e.g., abc.txt).

  • mode: Mode of file operation (e.g., "r", "w", "a").

File Modes:

• Six modes available:

  • r: Read mode.

  • w: Write mode (creates new file or truncates existing).

  • a: Append mode.

  • r+: Read and write mode.

  • w+: Read and write mode (creates new file or truncates).

  • a+: Append and read mode.

Closing a File with fclose

Importance of Closing Files

• Use fclose(fp); to close a file.

• Importance of closing:

  • Frees the file's buffer memory.

  • Allows other processes or pointers to access the file.

Summary of Key Functions

• Three main elements to remember for file handling:

  1. File Pointer (fp): Reference to the file in memory.

  2. Opening Function (fopen): Initializes the pointer and opens the file.

  3. Closing Function (fclose): Finalizes operations and frees resources.

Upcoming Topics

• Next video will cover specific operations in detail:

  • Reading and writing data using functions like fprintf, fscanf, fputc, fgetc, fgets, and fputs.

• Practical implementation will be demonstrated with code examples.