ft_atoi.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_atoi.c                                          :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: hshinaga <hshinaga@student.42.fr>          +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/11/02 15:26:37 by hshinaga          #+#    #+#             */
/*   Updated: 2024/11/05 00:38:29 by hshinaga         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"

static int	ft_isspace(char c)
{
	return (c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\v'
		|| c == '\f');
}

static int	ft_check_overflow(long result, int sign)
{
	if (result * sign > 2147483647)
		return (-1);
	if (result * sign < -2147483648)
		return (0);
	return (1);
}

int	ft_atoi(const char *str)
{
	int		sign;
	long	result;

	sign = 1;
	result = 0;
	while (ft_isspace(*str))
		str++;
	if (*str == '-' || *str == '+')
	{
		if (*str == '-')
			sign = -1;
		str++;
	}
	while (*str >= '0' && *str <= '9')
	{
		result = result * 10 + (*str - '0');
		if (ft_check_overflow(result, sign) != 1)
			return (ft_check_overflow(result, sign));
		str++;
	}
	return ((int)(result * sign));
}