ft_atoi.c

/* ************************************************************************** */
/*	                                                                        */
/*                                                        :::      ::::::::   */
/*   ft_atoi.c                                          :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: abertran <abertran@student.42.fr>          +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2022/09/26 18:02:54 by abertran          #+#    #+#             */
/*   Updated: 2022/09/26 18:04:12 by abertran         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"

/* convierte un string en int */

int	ft_atoi(const char *str)
{
	int				i;
	int				s;
	unsigned long	res;

	i = 0;
	s = 1;
	res = 0;
	while (str[i] == 32 || (str[i] >= 9 && str[i] <= 13))
		i++;
	if (str[i] == '-' || str[i] == '+')
	{
		if (str[i] == '-')
			s = -1;
		i++;
	}
	while (str[i] >= '0' && str[i] <= '9')
	{
		res = (res * 10) + (str[i] - '0');
		if (res > 9223372036854775808UL && s == -1)
			return (0);
		if (res > 9223372036854775807UL && s == 1)
			return (-1);
		i++;
	}
	return (res * s);
}