get_next_line

This project is part of the 42 curriculum and aims to create a function that returns, on each call, one line read from a file descriptor. It is an excellent opportunity to practice controlled file reading, the use of buffers, and static variables in C.

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📚 Objective

Implement the function get_next_line() capable of returning the next available line from a file descriptor, correctly preserving the state between successive calls. The return must include the newline character \n, except at the end of the file.

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🚫 Restrictions

• Use of libft is forbidden. No external custom functions may be used.
• Only the functions read, malloc, and free are allowed.
• Global variables are prohibited.
• lseek() is forbidden.

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✅ Mandatory Part

The function must have the following prototype:

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char *get_next_line(int fd);

• Must work with any valid file descriptor.
• Must read and return one line per call.
• Must return NULL in case of error or end of file.
• The project must be compilable with:

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cc -Wall -Wextra -Werror -D BUFFER_SIZE=<n> get_next_line.c get_next_line_utils.c

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🔁 Bonus Part

The bonus version of the project was successfully implemented and includes:

• Support for multiple file descriptors simultaneously.
• Use of only one static variable per call.
• Modular structure, with the following additional files:

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get_next_line_bonus.c
get_next_line_bonus.h
get_next_line_utils_bonus.c

To compile the bonus:

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cc -Wall -Wextra -Werror -D BUFFER_SIZE=<n> get_next_line_bonus.c get_next_line_utils_bonus.c

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🧪 Usage Example

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

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

    while ((line = get_next_line(fd)) != NULL)
    {
        printf("%s", line);
        free(line);
    }
    close(fd);
    return 0;
}

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📝 Considerations

• The project was implemented with a focus on performance and readability.
• Memory management was carefully handled to avoid leaks and undefined behavior.
• Tested with different BUFFER_SIZE values, including 1, 42, 9999, and 1000000.

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✅ Status

• Mandatory part completed
• Bonus part completed
• Validation with multiple file descriptors
• Validation with standard input (stdin)