ft_printf

A lightweight reimplementation of the C standard library function printf — ft_printf prints formatted output to stdout.
This repository contains a minimal, portable implementation intended for learning and assessment (commonly used as a 42-school project).

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Table of contents

• About
• Features
• Supported conversions & flags
• Requirements
• Installation / Build
• Usage
• Examples
• Testing
• Development notes
• Contributing
• License
• Author
• Contact

About

ft_printf is a small, educational implementation of printf. The goal is to reproduce the behavior of the standard printf for a subset of conversion specifiers and flags, handling formatting, field width and precision, and variable argument lists.

This project is useful for:

• Learning about variadic functions (stdarg.h)
• Practicing string formatting and buffer management in C
• Implementing and testing formatting logic for different data types

Features

• Implements core printf-like formatting
• Supports integer, unsigned, hex, pointer, char and string conversions
• Handles field width and precision
• Handles left alignment and zero-padding
• Small, dependency-free C implementation suitable for embedding or testing

Supported conversions & flags

Included in this implementation:

• Conversion specifiers: %c, %s, %p, %d, %i, %u, %x, %X, %%
• Flags: None

Note: Behavior may differ in edge cases from the system printf. Consult the source for exact supported behavior and limitations.

Requirements

• POSIX-compatible OS (Linux, macOS)
• C compiler (gcc, clang)
• make

Installation / Build

Clone the repository and build with the provided Makefile:

git clone https://github.com/AdnilsonPinheiro/ft_printf.git
cd ft_printf
make

Make targets (may vary):

• make — build the library or binary
• make clean — remove object files
• make fclean — remove binaries and library
• make re — fclean + make

Usage

Call ft_printf as you would call printf:

#include "ft_printf.h" // path may vary

int main(void)
{
    ft_printf("Hello %s, number: %d, hex: %#x\n", "world", 42, 255);
    return 0;
}

Examples

Some example outputs:

• ft_printf("%%\n"); -> prints "%"

• ft_printf("Char: %c\n", 'A');

• ft_printf("String: %.5s\n", "HelloWorld"); -> prints "Hello"

• ft_printf("Pointer: %p\n", ptr);

• ft_printf("Hex: %08x\n", 255); -> prints "000000ff"

• You can manually compare behavior to the system printf for many cases. Automating comparisons with a test harness is recommended to catch edge cases.

Development notes

• Payed close attention to memory management: avoided leaks and buffer overruns.
• Worked incrementally: implemented conversions one-by-one and added unit tests.
• Used valgrind during development to detect invalid memory accesses:

Contributing

Contributions are welcome. Suggested workflow:

1. Fork the repository
2. Create a feature branch: git checkout -b feat/description
3. Add tests for new behavior
4. Open a pull request describing the change

License

This repository is provided under the MIT License by default. Replace with your preferred license if different.

Author

• Adnilson Pinheiro — https://github.com/AdnilsonPinheiro

Contact

For questions or improvements, open an issue or pull request in the repository.