diff --git a/Makefile b/Makefile
index 9d6a583..e507ce0 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,7 @@ ft_strlcat.c ft_toupper.c ft_tolower.c ft_strchr.c ft_strrchr.c ft_strncmp.c \
 ft_memchr.c ft_memcmp.c ft_strnstr.c ft_atoi.c ft_calloc.c ft_strdup.c \
 ft_substr.c ft_strjoin.c ft_strtrim.c ft_split.c ft_itoa.c ft_strmapi.c \
 ft_striteri.c ft_putchar_fd.c ft_putstr_fd.c ft_putendl_fd.c ft_putnbr_fd.c \
-ft_get_size.c ft_power.c
+ft_get_size.c ft_power.c ft_atoi_check.c
 OBJS = ${SRCS:.c=.o}
 BONUS_SRCS = ft_lstnew.c ft_lstadd_front.c ft_lstsize.c ft_lstlast.c \
 ft_lstadd_back.c ft_lstdelone.c ft_lstclear.c ft_lstiter.c ft_lstmap.c 
diff --git a/ft_atoi_check.c b/ft_atoi_check.c
new file mode 100644
index 0000000..b549055
--- /dev/null
+++ b/ft_atoi_check.c
@@ -0,0 +1,50 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_atoi_check.c                                    :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: erey-bet <marvin@42.fr>                    +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2022/07/21 08:21:05 by erey-bet          #+#    #+#             */
+/*   Updated: 2022/12/08 16:37:19 by erey-bet         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "libft.h"
+
+static int	ft_isspace(char c)
+{
+	if (c == ' ' || c == '\f'
+		||c == '\n' || c == '\r' || c == '\t' || c == '\v')
+		return (1);
+	return (0);
+}
+
+int	ft_atoi_check(const char *nptr)
+{
+	long	result;
+	int		sign;
+
+	while (ft_isspace(*nptr))
+		nptr++;
+	sign = 1;
+	if (*nptr == '+' || *nptr == '-')
+	{
+		if (*nptr == '-')
+			sign = -1;
+		nptr++;
+	}
+	result = 0;
+	while (*nptr >= '0' && *nptr <= '9')
+	{
+		result = result * 10 + *nptr++ - '0';
+		if ((result > 2147483647 && sign == 1)
+			|| (result > 2147483648 && sign == -1))
+			return (0);
+	}
+	if (*nptr--)
+		return (0);
+	if (*nptr == '-' || *nptr == '+')
+		return (0);
+	return (1);
+}
diff --git a/libft.h b/libft.h
index aceddd6..7546f2e 100644
--- a/libft.h
+++ b/libft.h
@@ -66,5 +66,6 @@ void	ft_lstdelone(t_list *lst, void (*del)(void*));
 void	ft_lstclear(t_list **lst, void (*del)(void*));
 void	ft_lstiter(t_list *lst, void (*f)(void *));
 t_list	*ft_lstmap(t_list *lst, void *(*f)(void *), void (*del)(void *));
+int	ft_atoi_check(const char *nptr);
 
 #endif