ft_printf

A custom implementation of the standard C printf function, managing variadic arguments and complex string formatting.

2021-06-01

ft_printf

A reimplementation of printf in C without touching any formatted-output functions. It walks the format string character by character, and when it finds a % it dispatches to the right handler for that specifier.

Supported conversions

Specifier	Output
%c	Single character
%s	String (prints `(null)` for NULL pointers)
%p	Pointer in hex
%d / %i	Signed decimal integer
%u	Unsigned decimal integer
%x	Hex lowercase
%X	Hex uppercase
%%	Literal percent sign

Signature

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

Returns the number of characters written, or -1 on error. Same contract as the real printf.

How it works

ft_printf("Dec: %d | Hex: %x\n", 42, 42)
                  |           |
                  |           ft_hexalow(42) -> "2a"
                  ft_putnbr(42) -> "42"

Usage

#include "ft_printf.h"
 
ft_printf("Hello, %s!\n", "world");
ft_printf("Dec: %d | Hex: %x | Ptr: %p\n", 255, 255, &main);

make
gcc main.c libftprintf.a -o program

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