Let's talk about: GNL 💬

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🦮 Summary: 🦮

🔗 What is GNL

🔗 Mandatory part

🔗 How to use it

What is GNL? 🤔

The GNL (Get_next_line) is the first project with a higher level of difficulty both in technical aspects and in visualizing and understanding the process of creating it. At first, we have two ways to code it: Linked list or with arrays.

I chose to use the linked list, seeing as I love learning new concepts and this new data structure seemed very fun. So, I decided to start by studying about linked lists, and a great start was to follow the videos from the CodeVault channel:

But to summarize, a linked list is a sequence of elements, where each element is connected to the next one by a pointer. Unlike arrays, the elements are not placed contiguously in memory, which allows for efficient insertions and deletions as it doesn't require shifting elements around. Each element, known as a node, contains the data and a reference (or a link) to the next node in the sequence, making the structure flexible and dynamic.

Mandatory part 📑

The mandatory part of the project states that the Get_next_line() function must read a line from a file descriptor. What does this mean? It means we must read up to the '\n'. And what if there is no '\n'? Then we must read until the end of the file, i.e., until '\0'. If something goes wrong, we return NULL. Sounds quite straightforward, doesn't it?

Important notes:

• The GNL function must be prototyped as follows: char *get_next_line(int fd);

• The return value is a line that has been read ( NULL if there is nothing else to read, or an error occurred ).

• The function returns its result without '\n' if there is one.

• External functions allowed: read, malloc, free.

• The GNL function must be able to compile the BUFFER_SIZE value directly on the command line with -D BUFFER_SIZE=\<value>

• But, it should also run without a BUFFER_SIZE defined on the command line

• Remember that your program must compile with -Wall -Wextra -Werror

• You must only deliver the following files to your repository: get_next_line.c, get_next_line_utils.c, get_next_line.h

How to use it? 🤔

First step, clone my repository in the location where you will run it.

git clone https://github.com/Chrystian-Natanael/Get_next_line.git

Then, simply include the header file in your main file to have access to the get_next_line() function.

# include "get_next_line.h"

Finally, just call the function in your main file, passing a file descriptor. Make sure you have a variable of type char * to receive the return of the function. (Which is the read line).

char	*line;

line = get_next_line(fd);

Below we have an example of a main file, just make sure you have a test.txt file at the root of your repository:

# include "get_next_line.h" // for use get_next_line
# include <stdio.h> // for use printf
# include <fcntl.h> // for use open

int	main(void)
{
	int		fd;
	char	*line;

	fd = open("test.txt", O_RDONLY); // open file
	line = get_next_line(fd); // first line
	printf("%s\n", line); // print first line
	free(line); // free first line
	close(fd); // close file
	return (0);
}