ft_atoi.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_atoi.c                                          :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: ysaito <ysaito@student.42tokyo.jp>         +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2020/06/23 10:19:28 by ysaito            #+#    #+#             */
/*   Updated: 2021/11/01 20:37:51 by ysaito           ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"

int	ft_atoi(const char *str)
{
	long	num;
	int		negative;
	int		count;

	num = 0;
	negative = 1;
	count = 0;
	while (*str == ' ' || *str == '\t' || *str == '\n' \
	|| *str == '\v' || *str == '\f' || *str == '\r')
		str++;
	if (*str == '-' || *str == '+')
	{
		if (*str == '-')
			negative = -1;
		str++;
	}
	if (!('0' <= *str && *str <= '9'))
		return (0);
	while ('0' <= *str && *str <= '9')
	{
		num = num * 10 + (*str - '0');
		str++;
	}
	return (num * negative);
}