ft_strtol.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_strtol.c                                        :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: oadhesiv <oadhesiv@student.21-school.ru>   +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/04/25 14:17:03 by oadhesiv          #+#    #+#             */
/*   Updated: 2020/06/01 01:19:00 by oadhesiv         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"

static t_byte	ft_issign(char c)
{
	if (c == '+' || c == '-')
		return (1);
	return (0);
}

/*
** base is not implemented
*/

long			ft_strtol(const char *str, char **endptr, int base)
{
	t_ulong	ret;
	char	sign;
	size_t	i;

	base = 10;
	ret = 0;
	sign = 1;
	i = 0;
	while (str[i] && ft_isspace(str[i]))
		i++;
	if (ft_issign(str[i]))
		sign = str[i++] == '-' ? -1 : 1;
	if (ft_isdigit(str[i]))
		while (str[i] && ft_isdigit(str[i]))
		{
			if (ret > LONG_MAX / base
				|| (t_byte)(str[i] - 48) > LONG_MAX - ret * base)
				return (sign == -1 ? LONG_MIN : LONG_MAX);
			ret = ret * base + str[i] - 48;
			i++;
		}
	*endptr = (char*)(str + i);
	return (sign * ret);
}