This project has been created as part of the 42 curriculum by gvoelkne.

ft_printf#

Description#

Reimplementation of the C standard library's printf function. This project implements formatted output to stdout, supporting the following format specifiers:

• %c - single character
• %s - string
• %d, %i - signed decimal integer
• %u - unsigned decimal integer
• %x - unsigned hexadecimal (lowercase)
• %X - unsigned hexadecimal (uppercase)
• %p - pointer address
• %% - literal percent sign

Instructions#

# Build the static library
make

# Clean object files
make clean

# Clean object files and library
make fclean

# Rebuild from scratch
make re

To use in another project, compile with the library:

cc your_file.c -L. -lftprintf -o your_program

Algorithm and Data Structures#

The implementation uses a modular approach:

1. Main loop (ft_printf): Parses the format string, identifies format specifiers, and dispatches to appropriate handlers.

2. Variadic arguments (va_list): Uses stdarg.h to access variable arguments passed to the function.

3. Type-specific handlers:

   • Character and string output handled directly via write() syscalls
   • Integer types converted to strings using ft_ntoa (signed) and ft_untoa (unsigned)
   • Pointers formatted as hexadecimal with 0x prefix via ft_putptr

4. Helper functions: Memory-safe utilities (e.g. ft_calloc, ft_strdup) and string manipulation (e.g. ft_strlen, ft_strlower) support the core functionality.

The design prioritizes clarity and correctness over performance, with each format specifier delegated to a dedicated function.

Resources#

• printf(3) man page
• stdarg.h documentation
• 42 School subject materials on variadic functions
• Mistral AI as a mental sparring partner.