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

Description

The ft_printf project involves reimplementing the C printf() function, requiring an understanding of variadic functions.

Instructions

Compile using cc -Wall -Werror -Wextra. If using the Makefile: make all compiles all source files, make clean removes all .o files, and make fclean removes the .a library file.

Resources

C応用特別編 可変長引数の仕組み
軽くprintf関数を自作する
man 3 printf

How AI was used

• Reviewed the conversion logic (%d, %x, %p, INT_MIN handling) and the write() error propagation across all source files, and identified bugs.
  
• Clarifying conceptual questions during learning
  
• Translating my own Japanese draft of this README into English

Usage Example

To test various cases and edge cases, copy and paste the code below into main.c. (The code below compares the original C printf() with ft_printf().)

#include <stdio.h>
#include <limits.h>
#include "ft_printf.h"

int main(void)
{
    ft_printf("char: %c\n", 'A');
    ft_printf("str: %s\n", "hello");
    ft_printf("%d\n", ft_printf("int: %d\n", -42));
    ft_printf("%d\n", ft_printf("int: %d\n", 01234567));
    printf("%d\n", printf("int :%d\n", -42));
    printf("%d\n", printf("int :%d\n", 01234567));

    ft_printf("unsigned: %u\n", 42u);
    ft_printf("hex: %x\n", 255);
    ft_printf("HEX: %X\n", 255);
    ft_printf("%d\n", ft_printf("ptr: %p\n", (void *)0x1234));
    ft_printf("percent: %%\n");
    int ret1 = printf("hello %d\n", 42);
    int ret2 = ft_printf("hello %d\n", 42);
    printf("printf returned: %d\n", ret1);
    ft_printf("ft_printf returned: %d\n", ret2);
    ft_printf("abc%");

    ft_printf("%d\n", ft_printf("awesome!!\n"));
    printf("%d\n", printf("awesome!!\n"));

    ft_printf("%u\n", 0);
    ft_printf("%x\n", 0);
    ft_printf("%X\n", 0);
    ft_printf("%s\n", "");
    ft_printf("%s\n", NULL);
    ft_printf("%p\n", NULL);
    ft_printf("%%d\n");

    ft_printf("%c%s%d%u%x%X%%\n", 'A', "test", -1, 1u, 255, 255);
    printf("%c%s%d%u%x%X%%\n", 'A', "test", -1, 1u, 255, 255);
    printf("%u\n", 0);
    printf("%x\n", 0);
    printf("%X\n", 0);
    printf("%s\n", "");
    printf("%%d\n");

    ft_printf("%d\n", INT_MIN);
    ft_printf("%i\n", INT_MAX);

    printf("%d\n", INT_MIN);
    printf("%i\n", INT_MAX);

    ft_printf("%u\n", 4294967295);
    ft_printf("%x\n", 4294967295);
    ft_printf("%X\n", 4294967295);
    return (0);
}

Explanation of the Chosen Algorithm and Data Structure

Format	Data Type	Conversion Method
%c	single character	Writes a single character using write.
%s	string	Computes the string length, then writes it using write.
%p	The void * pointer argument must be printed in hexadecimal format	Writes "0x", then converts the address to hexadecimal using a recursive function and a lookup table (base).
%d	decimal (base 10) number	Converts and outputs the number in decimal using a recursive function.
%i	integer in base 10	Converts and outputs the number in decimal using a recursive function.
%u	unsigned decimal (base 10) number	Converts and outputs the unsigned number in decimal using a recursive function.
%x	number in hexadecimal (base 16) lowercase format	Converts and outputs the number in hexadecimal using a recursive function and a lowercase lookup table (base).
%X	number in hexadecimal (base 16) uppercase format	Converts and outputs the number in hexadecimal using a recursive function and an uppercase lookup table (base).
%%	Percent sign	Outputs a literal % character.

If an output error is encountered during write, a negative value is returned.