3_print_hex.c

/* ***************************************************************************
 * Author  : Kura Peng (kpeng) <https://github.com/sayakura>
 * Created : 2018/10/05
 * Updated : 2018/10/05
 * ***************************************************************************/

#include <unistd.h>

char *g_base = "0123456789abcdef";

void	pc(int c)
{
	write(1, &c, 1);
}

int		atoi(char *str)
{
	int i = 0;
	unsigned int result = 0;
	while (str[i] >= '0' && str[i] <= '9')
	{
		result = result * 10 + str[i] - '0';
		i++;
	}
	return (int)(result);
}

void	ph(int num)
{
	if (num >= 16)
		ph(num / 16);
	pc(g_base[num % 16]);
}

int		main(int ac, char **av)
{
	if (ac != 2)
	{
		pc('\n');
		return (0);
	}
	else
	{
		int num = atoi(av[1]);
		ph(num);
		pc('\n');
	}
	return (0);
}
/*
Assignment name  : print_hex
Expected files   : print_hex.c
Allowed functions: write
--------------------------------------------------------------------------------

Write a program that takes a positive (or zero) number expressed in base 10,
and displays it in base 16 (lowercase letters) followed by a newline.

If the number of parameters is not 1, the program displays a newline.

Examples:

$> ./print_hex "10" | cat -e
a$
$> ./print_hex "255" | cat -e
ff$
$> ./print_hex "5156454" | cat -e
4eae66$
$> ./print_hex | cat -e
$
*/