get_next_line

A C function that reads any valid file line by line until the end from a file descriptor.

Contents

• What is get_next_line?
• Why would I use/try it?
• How do I use it?
• How do I test my own code?

What is get_next_line?

get_next_line is an individual project at 42 that teaches you how to open/write data in a file, and how to manage memory (does not contain memory leaks).

Why would I use/try it?

The goal is to get better at C, and understand memory management. You can only use those three standard library functions:

• read
• malloc
• free

, but you can also use functions from your personal library.

To make code even better, I decided to implement the function in less than 25 lines (we have a norm of coding at 42 School, such as 1 function should have only 25 lines of code).

How do I use it?

I added a file called test.c, it takes a file name as an argument, opens it and passes the file descriptor (fd) to get_next_line until get_next_line returns -1 or 0.

Note: get_next_line returns -1, 0, 1 depending on wether an error has occurred, the reading has been completed or a line has been read respectively.

Download/clone this repo.

Get into it and build the library:

cd get_next_line
git clone https://github.com/asansyzb/get_next_line libft
make -C libft/

Build the executable:

gcc -Wall -Wextra -Werror -I./libft/ -L./libft -lft -o gnl get_next_line.c test.c

-I tells the compiler where your library header files are. ./libft/ in this case

-L tells it where your library resides. ./libft here

-l takes the name of your library. This is the set of characters that come after lib in your library name.

NOTE: -L and -l might look a little bit too much, you could replace those flags with libft/libft.a if you want.

Alright, the last command created a gnl executable in your directory. Now test it with:

./gnl sample.txt

It should read the whole file to you. Kinda like a basic cat implementation.

NOTE: The poem in the text file is Abai Qunanbaiv's famous Black Of My Eye ;)

How do I test my own code?

You can do as above and use the test.c file I added. This is a pretty rudimentary test, if you want to try some deep tests, let me introduce you to the amazing 42FileChecker by [@jgigault][18].

Assuming you read the project instructions and coded your own get_next_line

1. Go back to the root directory and download @jgigault's 42FileChecker:

    cd ..
    git clone https://github.com/jgigault/42FileChecker
   

2. Go into the test folder and run the test:

    cd 42FileChecker
    sh 42FileChecker.sh
   

Press 5 to select tests for get_next_line, press 1 to install moulitest as an external repo, then 1 to configure the tests, now you handle the path to your get_next_line and then choose which test to run on your project.

All of the instructions I used was copied/paraphrased from other 42 student.

Have fun :)