ft_printf

Description

This goal goal of this project is to recreate the behavior of the printf function from stdio library in C.

We don't actually have to implement everything, since the mandatory part only covers a limited selection of specifiers:

Specifier	Description
%c	Character. Prints a single character.
%s	String. Prints a sequence of characters (string).
%p	Pointer. Prints a memory address.
%d	Signed decimal integer.
%i	Signed decimal integer (same as %d).
%u	Unsigned decimal integer.
%x	Unsigned hexadecimal integer (lowercase).
%X	Unsigned hexadecimal integer (uppercase).
%%	Prints a literal % character.

The function prototype is:

int ft_printf(char const *format, ...)

Wait, int is the output type? Yep, turns out printf outputs the number of characters it prints!

Tips

1. RTFM!

Read the manual for printf here.

It should contain all the information you need to know to correctly implement the function.

2. Variadic functions

printf can take as many arguments as the user wants, that's why we can't simply fix n parameters.

Using ellipsis ... as the last parameter declares a variadic function.

Reading about stdarg library will prove useful. You can do it here

Macro/Type	Description
va_start	Enables access to variadic function arguments. Defined in header <stdarg.h>.
va_arg	Accesses the next variadic function argument. Defined in header <stdarg.h>.
va_copy	(C99) Makes a copy of the variadic function arguments. Defined in header <stdarg.h>.
va_end	Ends traversal of the variadic function arguments. Defined in header <stdarg.h>.
va_list	Holds the information needed by va_start, va_arg, va_end, and va_copy (typedef).

3. Project structure

You can use as many directories and C files/headers as you want, I structured my project as follows:

├── ft_printf.c
├── ft_printf.h
├── libft
│   ├── *.c
│   └── libft.h
├── Makefile
└── utils
    ├── ft_printf_char.c
    ├── ft_printf_hex.c
    ├── ft_printf_int.c
    ├── ft_printf_pointer.c
    ├── ft_printf_string.c
    └── ft_printf_uint.c

Where ft_printf.c contains the general, abstract implementation logic of printf. libft is a directory with useful functions that are also used in utils, a directory specifically created for printing each specifier format.

4. Test before pushing!

Don't risk losing evaluation points! Some dedicated students have built useful testers that cover most of the edge cases that Moulinette might throw at you. I personally used francinette.

Here’s how to set it up on your machine:

1. Install it with the following command:

bash -c "$(curl -fsSL https://raw.github.com/xicodomingues/francinette/master/bin/install.sh)"

2. Navigate to the francinette directory and install the required Python libraries:

python3 -m pip install -r requirements.txt

NOTE: It’s a good idea to use a virtual environment. You can create one with: python3 -m venv .venv. Then, activate it with: source .venv/bin/activate before running the command above.

3. Create an alias for running francinette:

Add the following line to your .zshrc file in your home directory:

alias paco="python3 /home/<intra login>/francinette/main.py"

4. Create a Makefile and test your functions!

You’ll need a Makefile to run the testers. Once it's set up, simply execute the following command in your project directory:

paco