Libft/libft/ft_atoi.c

#include "libft.h"

int	ft_atoi(const char *str)
{
	int		i;
	int		j;
	int		m;

	i = 0;
	j = 0;
	m = 1;
	while ((str[i] >= 9 && str[i] <= 13) || str[i] == ' ')
		i++;
	if (str[i] == '-' || str[i] == '+')
	{
		if (str[i] == '-')
			m = -m;
		i++;
	}
	while (str[i] >= '0' && str[i] <= '9')
	{
		j = (j * 10) + (str[i] - '0');
		i++;
	}
	return (j * m);
}