ft_printf

This repository contains my implementation of the ft_printf function, a core project in the 42 School curriculum.

The goal of this project is to recreate the standard C printf function while meeting specific requirements and constraints, deepening the understanding of variadic functions, formatted output, and memory management.

About ft_printf

• ft_printf is a variadic function, meaning it accepts a variable number of arguments.
• The first argument is a format string that defines how the subsequent arguments are formatted and displayed.
• The function processes the format string, parsing specifiers like %d, %s, %c, etc., and outputs the corresponding formatted values.

Key Concepts

• Variadic Functions:

  • The <stdarg.h> library is used to handle variadic functions, enabling the processing of a variable number of arguments.
  • Key macros:
    • va_start: Initializes the va_list for use.
    • va_arg: Retrieves the next argument from the list.
    • va_end: Cleans up the va_list after processing.

• Return Type:

  • The function returns the total number of characters printed.
  • If an error occurs, ft_printf returns -1.

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Folder Structure

ft_printf/
|
├── Makefile
|
├── ft_printf.h
|
├── ft_printf.c
|
├── ft_printf_digits.c
|
├── ft_printf_hex.c
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├── ft_printf_words.c
|
└── main.c

Functions Overview

Function	Description
ft_printf(const char *str, ...)	The main function that processes the format string and handles the variadic arguments. It returns the total number of characters printed.
ft_printf_format(char specifier, va_list arg_ptr)	A helper function that processes individual format specifiers (e.g., %c, %d, %s).
ft_printf_c(int c)	Handles the %c format specifier and prints a character.
ft_printf_s(char *s)	Handles the %s format specifier and prints a string.
ft_printf_d(int n)	Handles the %d format specifier and prints a signed integer.
ft_printf_u(unsigned int n)	Handles the %u format specifier and prints an unsigned integer.
ft_printf_p(void *ptr)	Handles the %p format specifier and prints a pointer address.
ft_printf_x(unsigned int n, char specifier)	Handles the %x and %X format specifiers to print a hexadecimal value (lowercase/uppercase).
ft_printf_hex(unsigned long n)	Prints a hexadecimal value (lowercase) of the given unsigned long integer.
ft_printf_hex_upper(unsigned long n)	Prints a hexadecimal value (uppercase) of the given unsigned long integer.

How to Run

1. Clone the repository

git clone https://github.com/your-username/ft_printf.git
cd ft_printf

2. Compile the library

make

This will generate the static library:

libftprintf.a

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How to Use

Include the header in your C file:

#include "ft_printf.h"

Compile your program with the library:

cc main.c libftprintf.a

Then run:

./a.out

Example

Example program using ft_printf:

#include "ft_printf.h"

int main(void)
{
    int len;

    len = ft_printf("Hello %s!\n", "World");
    ft_printf("Printed %d characters\n", len);

    ft_printf("Character: %c\n", 'A');
    ft_printf("Decimal: %d\n", 42);
    ft_printf("Unsigned: %u\n", 42);
    ft_printf("Hex lowercase: %x\n", 255);
    ft_printf("Hex uppercase: %X\n", 255);
    ft_printf("Pointer: %p\n", &len);

    return (0);
}

Output

Hello World!
Printed 13 characters
Character: A
Decimal: 42
Unsigned: 42
Hex lowercase: ff
Hex uppercase: FF
Pointer: 0x7ffee3b6c9ac