📜 get_next_line

Reading a line from a file descriptor is far too tedious… so let’s fix that 😎

---

🧠 Introduction

The get_next_line project is about writing a function that returns a line read from a file descriptor —
each call gives you the next line until the file ends (or an error occurs).

You’ll also discover one of the most powerful concepts in C: static variables ⚡

---

🎯 Goals

• Understand and use static variables 🧍‍♂️
• Learn how to manage persistent data between function calls
• Practice working with file descriptors and the read() function
• Build a robust line reader for any text input (file or stdin)

---

⚙️ Mandatory Part

Function name	get_next_line
Prototype	char *get_next_line(int fd);
Files to turn in	get_next_line.c, get_next_line_utils.c, get_next_line.h
Parameters	fd → The file descriptor to read from
Return value	A line that has been read — or NULL if there’s nothing else to read or an error occurs
External functions	read, malloc, free
Forbidden	lseek, global variables, and your libft

---

🧩 Behavior

• The function reads from the file descriptor one line at a time.
• Each call to get_next_line() should return the next line.
• The newline character \n must be included in the returned string —
  except for the last line of the file if it doesn’t end with \n.
• If there’s nothing left to read or an error occurs → NULL is returned.
• Must work for both file input and standard input (stdin).

---

💡 Compilation

Your code will be compiled with the following command:

cc -Wall -Wextra -Werror -D BUFFER_SIZE=42 get_next_line.c get_next_line_utils.c

• BUFFER_SIZE defines how many bytes are read at once.
• You can compile with any buffer size value (1, 42, 9999, etc.) for testing.
• You must handle compilation with or without the -D BUFFER_SIZE flag.

Example:

cc -Wall -Wextra -Werror -D BUFFER_SIZE=100 main.c get_next_line.c get_next_line_utils.c

🧱 Project Structure

get_next_line/
│
├── get_next_line.c
├── get_next_line_utils.c
├── get_next_line.h
├── Makefile
└── main.c  (for your tests)

🧪 Example Test

#include "get_next_line.h"
#include <fcntl.h>
#include <stdio.h>

int main(void)
{
    int fd = open("test.txt", O_RDONLY);
    char *line;

    while ((line = get_next_line(fd)))
    {
        printf("%s", line);
        free(line);
    }
    close(fd);
}

📦 Makefile Rules

Rule	Description
all	Compiles the project
clean	Removes object files
fclean	Removes object files and binary
re	Cleans and rebuilds everything

🧹 Norm & Memory

• Code must comply with the 42 Norm 🧾
• No memory leaks or double frees allowed ❌
• No unexpected crashes (segfaults, bus errors, etc.) 🚫

🧾 Evaluation Checklist

✅ Returns one line at a time

✅ Works with multiple BUFFER_SIZE values

✅ Correctly handles EOF and errors

✅ Includes \n in output when needed

✅ Compiles with all required flags

✅ Passes Norminette

✅ No memory leaks or global variables

🧑‍💻 Author

Ayoub Sadouri

42 Network – get_next_line project

“Reading files one line at a time... because why make life easy?” 🤓

📬 Contact

Want to collaborate or just geek out about low-level C programming? Reach out anytime!

🌐​ https://ayoubsadouri.com

⭐ If this repo made your life easier, don’t forget to star it!