ft_printf

Because ft_putnbr() and ft_putstr() aren't enough

A reimplementation of the printf function from the C standard library as part of the 42 school curriculum.

This project is part of the Common Core curriculum at 42 School. The goal is to recreate the functionality of the standard C library function printf() to deepen understanding of variadic functions, string parsing, and formatted output in C.

Table of Contents

• Overview
• Supported Format Specifiers
• Supported Flags
• How to Use
• Implementation Details
• Examples
• License

Overview

This project involves coding a library that contains a customized version of the printf() function, called ft_printf(). The function is designed to mimic the original printf() function but with a limited set of format specifiers and capabilities.

The ft_printf() function formats and prints its arguments, following format specifier strings that start with % to indicate that formatting will take place.

As specified in the 42 project brief, this implementation:

• Does not implement the buffer management of the original printf()
• Supports a specific set of conversions: cspdiuxX%
• Provides flag handling for advanced formatting

Supported Format Specifiers

Specifier	Description
%c	Prints a single character
%s	Prints a string
%p	Prints a void pointer in hexadecimal format
%d	Prints a decimal number (base 10)
%i	Prints an integer in base 10
%u	Prints an unsigned decimal number (base 10)
%x	Prints a number in hexadecimal (base 16) lowercase format
%X	Prints a number in hexadecimal (base 16) uppercase format
%%	Prints a percent sign

Supported Flags

The library also handles various flags to modify how values are printed:

Flag	Description
-	Left-justify within the given field width
0	Left-pads the number with zeroes instead of spaces when padding is specified
.	Precision that indicates minimum number of digits to be printed
+	Forces to precede the result with a plus or minus sign
	(Space) If no sign is going to be written, a blank space is inserted before the value
#	Alternate form - adds prefix 0x or 0X for hexadecimal values
Width	Minimum number of characters to output

How to Use

Compilation

git clone https://github.com/magalhaesm/printf.git
cd ft_printf
make

This will generate a library file libftprintf.a that you can link to your C projects.

Integration

When compiling your projects, link with the ft_printf library:

gcc -Wall -Wextra -Werror your_program.c -L. -lftprintf -I include/

Basic Usage

#include "ft_printf.h"

int main(void)
{
    ft_printf("Hello, %s!\n", "world");
    return (0);
}

Implementation Details

The implementation is structured into several components:

• Parser: Analyzes the format string and interprets format specifiers
• Printer: Handles the output of formatted data
• Type-specific handlers: Separate functions for each format specifier

Unlike the original printf(), this implementation does not use buffer management, making it more straightforward but potentially less efficient for multiple outputs.

Examples

// Basic string and character
ft_printf("Character: %c\n", 'A');
ft_printf("String: %s\n", "Hello, 42!");

// Numbers in different formats
ft_printf("Decimal: %d\n", 42);
ft_printf("Hexadecimal (lowercase): %x\n", 42);
ft_printf("Hexadecimal (uppercase): %X\n", 42);

// Pointers
int num = 42;
ft_printf("Pointer: %p\n", &num);

// Using flags
ft_printf("Zero-padded: %05d\n", 42);
ft_printf("Left-justified: %-10s\n", "Left");
ft_printf("Precision: %.3d\n", 42);
ft_printf("With sign: %+d\n", 42);
ft_printf("With space: % d\n", 42);
ft_printf("With alternate form: %#x\n", 42);

License

This project is licensed under the GNU General Public License v3 - see the LICENSE file for details.

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© 2022 mdias-ma - This project is released under the GNU GPL v3 license.