ft_atoi.c

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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_atoi.c                                          :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tgrekov <tgrekov@student.hive.fi>          +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2023/10/25 13:12:00 by tgrekov           #+#    #+#             */
/*   Updated: 2023/11/16 08:55:47 by tgrekov          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
 
#include "libft.h"
 
static int  ft_isspace(char c)
{
    return (c == ' ' || c == '\t' || c == '\n'
        || c == '\v' || c == '\f' || c == '\r');
}
 
int ft_atoi(const char *str)
{
    long    nbr;
    int     sign;
 
    while (ft_isspace(*str))
        str++;
    sign = 1;
    if (*str == '-' || *str == '+')
    {
        if (*str == '-')
            sign *= -1;
        str++;
    }
    nbr = 0;
    while (ft_isdigit(*str))
    {
        if (nbr > FT_LONG_MAX / 10 || (nbr == FT_LONG_MAX / 10 && *str > '7'))
        {
            if (sign == 1)
                return ((int) FT_LONG_MAX);
            return ((int) -FT_LONG_MAX - 1L);
        }
        nbr = nbr * 10 + (*(str++) - '0');
    }
    return (nbr * sign);
}