Description

Jason Zixu Zhou Oct-4-2024
Basic Concepts of File Operations
• File Types:
• Text Files: Store data in readable text format.
• Binary Files: Store data in binary format, not human-readable.
• Concept of File Streams:
• Definition: A stream represents a sequence of bytes.
• Visual Aid: Diagram showing a stream flowing from a file to a program.
Opening Files
• Using fopen() Function:
• Syntax: FILE *fopen(const char
*filename, const char *mode);
• Parameters: Explain filename and
mode.
• File Modes Explained:
• “r”: Open for reading. If the file does
not exist, the opening fails.
• “w”: Open for writing. If the file exists,
it is truncated to zero length.
• “a”: Open for appending. The file is
created if it does not exist.
• “r+”: Open for reading and writing
from the beginning.
Reading Files
• Reading Functions:
• fgetc(): Reads a single character.
• fgets(): Reads a string until newline or EOF.
• fread(): Reads multiple bytes, used in binary files.

Fread Source Code Analysis
• https://sourceware.org/git/?p=glibc.git;a=blob;f=libio/iofread.c;h= 3294fac5f5911d78f8f9d607e5b973a08c6727b2;hb=refs/heads/re lease/2.40/master

Line-by-Line Code Analysis:

_IO_fread function: the internal implementation of fread. buf is the destination buffer for the data read
size is the size of each data element
count is the number of elements to read
fp is a pointer to a FILE structure representing the file stream
Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Line-by-Line Code Analysis:

Writing Files
• Writing Functions:
• fputc(): Writes a single character.
• fputs(): Writes a string.
• fwrite(): Writes multiple bytes, used in binary files.
Closing Files
• Using fclose() Function:
• Syntax: int fclose(FILE *stream);
• Purpose: Ensure all data is written and resources are released.
• Importance:
• Data Integrity: Prevents data loss.
• Resource Management: Frees up system resources.
Example: Simple File Read/Write

Header Files
• Purpose of Header Files:
• Declare Functions: Ensure function calls are recognized.
• Define Macros: Simplify repetitive code.
• Define Data Structures: Share structures across files.
• Common Headers:
• List: Includes <stdio.h>, <stdlib.h>, and explanation of their common uses.
Creating Custom Header Files
• How to Create and Use:
• Creating .h Files: Tips on writing your own header files.
• Include Guards: #ifndef, #define, #endif to prevent duplicate inclusion.
• Example:

#pragma once
• What is #pragma once?
• A preprocessor directive used to prevent multiple inclusions of the same header file.
• Benefits:
• Simpler and less error-prone than traditional include guards.
• Supported by most modern compilers (e.g., GCC, Clang, MSVC).
Opening Binary Files
• Using fopen() for Binary Files:
• Append “b” to the mode string in fopen() function, e.g., “rb”, “wb”, “ab”, “rb+”, “wb+”, “ab+”.