问关于atoi函数

EN

#include <unistd.h>

int ft_atoi(char *str)
{
    int c;
    int sign;
    int result;

    c = 0;
    sign = 1;
    result = 0;
    while ((str[c] >= '\t' && str[c] <= '\r') || str[c] == ' ')
    {
        c++;
    }
    while (str[c] == '+' || str[c] == '-')
    {
        if (str[c] == '-')
            sign *= -1;
        c++;
    }
    while (str[c] >= '0' && str[c] <= '9')
    {
        result = (str[c] - '0') + (result * 10);
        c++;
    }
    return (result * sign);
}

#include <stdio.h>

int main(void)
{
    char *s = " ---+--+1234ab567";
    printf("%d", ft_atoi(s));
}