Custom printf function

This is a custom implementation of the printf function in C. It supports all the standard format specifiers, as well as some additional features.

Supported format specifiers

Format Specifier	Description
%%	Prints a percent sign
%c	Prints a single character
%s	Prints a string of characters
%d	Prints a decimal number
%i	Prints an integer in base 10 (Decimal)
%b	Prints a binary number
%u	Prints an unsigned integer
%o	Prints a number in base 8 (Octal)
%x	Prints a hexadecimal in lowercase
%X	Prints a hexadecimal in uppercase
%S	Prints a string with hex values of non-visible characters
%r	Prints a reversed string
%R	Prints the Rot13 interpretation of a string

Additional features

• Customizable width option

To print a number with a certain (minimum)width, say 5 spaces wide, the format specifier is %5d .Here are some sample cases and results. (We willuse the _ symbol to explicitly indicate a space.)

printf	produces
("%5d", 0)	_ _ _ _ _ 0
("%5d", 1560133635)	1560133635

• Plus Signs

To print the ouput number with a + sign

printf	produces
("%+d", 3)	+3

• Hash sign

To print the output to be prefixed with '0'

Compilation

To compile the _printf function along with the other source files, we can use the following command:

gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c; ./a.out

Examples

Here are some examples of how to use the _printf() function:

#include "_printf.h"

int main(void)
{
    void *addr = (void *) 0x7ffe637541f0;;

    _printf("%c\n", "c"); // c
    _printf("%s\n", "c is fun"); // c is fun
    _printf("%%\n"); // %
    _printf("%d\n", 12345); // 12345
    _printf("%i\n", 12345); // 12345
    _printf("%b\n", 98); // 1100010
    _printf("%S\n", "c is\nfun"); // is is\x0Afun
    _printf("%p\n", addr); // 0x7ffe637541f0

    return (0);
}