ft_printf

Recreation of the C standard library printf function, built from scratch as part of the 42 Madrid curriculum.

The goal was to understand variadic functions, format string parsing, and low-level data representation without relying on the original libc implementation.

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Project Structure

printf/
├── ft_printf.c   # Main function and format parser
├── ft_printf.h   # Header file
├── utils.c       # Helper functions
└── Makefile

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Supported Conversions

Specifier	Description
%c	Single character
%s	String
%p	Pointer address in hexadecimal
%d	Decimal integer
%i	Integer
%u	Unsigned decimal integer
%x	Hexadecimal (lowercase)
%X	Hexadecimal (uppercase)
%%	Literal percent sign

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Usage

Compilation

make        # compile
make clean  # remove object files
make fclean # remove object files and library
make re     # full rebuild

Using in your project

#include "ft_printf.h"

gcc main.c -L. -lftprintf -o program

Example

ft_printf("Hello, %s! Number: %d\n", "world", 42);
ft_printf("Pointer: %p | Hex: %x\n", ptr, 255);

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What I Learned

• Variadic functions — va_list, va_start, va_arg, va_end
• Format string parsing
• Base conversion (decimal, hexadecimal)
• Writing modular and reusable C code

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Author

Aitor Alonso Jusdado — 42 Madrid — LinkedIn