📚 Get Next Line

📝 Introduction

Get Next Line (GNL) is a crucial project at 42 School that challenges students to implement a function capable of reading a line from a file descriptor. This seemingly simple task introduces fundamental concepts in file I/O operations, memory management, and static variables in C.

"Reading a line from a fd is way too tedious" - This project solves that problem by creating a convenient function you'll likely use in many future projects.

This function will be an essential tool throughout your journey at 42, as it enables reading from files, standard input, or even network connections line by line.

🎯 Project Objectives

• Create a function that returns a line read from a file descriptor
• Learn about static variables in C
• Understand file descriptors and basic I/O operations
• Master dynamic memory allocation and management
• Implement buffer handling for efficient file reading
• Develop code that works regardless of buffer size

🛠️ Implementation Details

Core Function

char *get_next_line(int fd);

Returns a line read from a file descriptor, with the newline character included.

Files Structure

File	Description
get_next_line.c	Main function implementation
get_next_line.h	Header with function prototypes and definitions
get_next_line_utils.c	Helper functions for the main implementation

Key Components

Function	Description
get_next_line	Main function that returns the next line from a file descriptor
ft_read_st_save	Reads from file descriptor into buffer and appends to static variable
ft_get_line	Extracts a line from the saved content
ft_st_save	Updates the static variable by removing the line just extracted

💡 How It Works

1. File Reading Process:

   • The function reads BUFFER_SIZE bytes at a time from the file descriptor
   • Content is stored in a static variable to persist between function calls
   • Reading continues until a newline character is found or EOF is reached

2. Line Extraction:

   • When a newline is found, the function extracts everything up to and including the newline
   • The extracted line is returned to the caller
   • Remaining content stays in the static variable for the next call

3. Memory Management:

   • Dynamic memory allocation for the buffer and returned line
   • Careful freeing of memory to avoid leaks
   • Handling of edge cases (empty file, read errors, etc.)

🧪 Testing

The function was tested with:

• Various buffer sizes
• Multiple file descriptors simultaneously
• Binary files, empty files, and large text files
• Standard input and custom file descriptors

📋 Skills Developed

• File I/O operations in C
• Static variables and their appropriate use cases
• Dynamic memory allocation and management
• Buffer manipulation techniques
• Defensive programming and error handling
• Writing clean, maintainable code

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📊 Project Stats

Metric	Value
Final Score	100/100
Functions Implemented	4
Lines of Code	~150
Completion Time	1 week