Functions

1. fopen()

Purpose: Opens a file and returns a pointer to a FILE structure representing the file.

• Usage: fin = fopen(fname, "r");
• Parameters:
  • fname: The name of the file to open.
  • "r": The mode for opening (e.g., "r" for reading).
• Returns: A pointer to the FILE structure if successful, NULL if it fails.
• What to Learn: Understand different modes (r, w, a, etc.), handling errors, and file operations in C.

2. fseek()

Purpose: Moves the file pointer to a specific position in the file.

• Usage: ret = fseek(fin, 0, SEEK_END);
• Parameters:
  • fin: The file pointer.
  • 0: Offset in bytes (0 in this case).
  • SEEK_END: Move to the end of the file.
• Returns: 0 on success, 1 on failure.
• What to Learn: Seek modes (SEEK_SET, SEEK_CUR, SEEK_END), why seeking is important for random access in files.

3. ftell()

Purpose: Returns the current position of the file pointer.

• Usage: length = ftell(fin);
• Returns: The current position of the file pointer (number of bytes from the beginning), or 1L if an error occurs.
• What to Learn: Using ftell() to get file size after moving the pointer to the end with fseek().

4. fclose()

Purpose: Closes an opened file and frees resources associated with it.