feat(convert/atou): adding the atou function

- Can be usefull when the parsing of some project (like philosophers)

convert/ft_atou.c

@@ -0,0 +1,40 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_atou.c                                          :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: rparodi <marvin@42.fr>                     +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2023/11/08 17:22:41 by rparodi           #+#    #+#             */
+/*   Updated: 2025/09/08 10:16:01 by rparodi          ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include <stddef.h>
+
+static int	ft_check_space(int c)
+{
+	if (c == 32 || (c >= 9 && c <= 13))
+		return (1);
+	return (0);
+}
+
+size_t	ft_atou(const char *nptr)
+{
+	size_t	i;
+	size_t	number;
+
+	if (!nptr)
+		return (0);
+	i = 0;
+	number = 0;
+	while (nptr[i])
+	{
+		if (nptr[i] >= '0' && nptr[i] <= '9')
+			number = (number * 10) + nptr[i] - '0';
+		else
+			break ;
+		i++;
+	}
+	return (number);
+}

includes/convert.h

@@ -6,13 +6,15 @@
 /*   By: rparodi <rparodi@student.42.fr>            +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2024/10/31 14:57:24 by rparodi           #+#    #+#             */
-/*   Updated: 2025/09/05 16:07:54 by rparodi          ###   ########.fr       */
+/*   Updated: 2025/09/08 10:17:01 by rparodi          ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #ifndef CONVERT_H
 # define CONVERT_H
 
+# include <stddef.h>
+
 /**
  * @brief Converts integer to string
  *
@@ -29,6 +31,14 @@ char			*ft_itoa(int n);
  */
 int				ft_atoi(const char *nptr);
 
+/**
+ * @brief Converts string to size_t
+ *
+ * @param nptr the string that will be converted
+ * @return The unsigned long long on the string
+ */
+size_t	ft_atou(const char *nptr);
+
 /**
  * @brief Converts string to long long integer
  *