adding atoi_superscript and isdigit_superscript

srcs/ft_atoll.c

@@ -0,0 +1,39 @@
+
+#include "libft.h"
+
+long long ft_atoll(const char *str)
+{
+	long long nbr;
+	int i;
+	int sign;
+
+	i = 0;
+	sign = 1;
+	nbr = 0;
+
+	// skip leading whitespace
+	while (ft_isspace(str[i]))
+		i++;
+
+	// handle optional sign
+	if (str[i] == '-')
+		sign = -1;
+	if (str[i] == '+' || str[i] == '-')
+		i++;
+
+	// parse digits with overflow check for `long long`
+	while (str[i] >= '0' && str[i] <= '9')
+	{
+		// check if multiplying by 10 would overflow
+		if (nbr > LLONG_MAX / 10)
+			return (sign > 0) ? LLONG_MAX : LLONG_MIN;
+		// check if adding the next digit would overflow
+		if (nbr == LLONG_MAX / 10 && (str[i] - '0') > LLONG_MAX % 10)
+			return (sign > 0) ? LLONG_MAX : LLONG_MIN;
+
+		nbr = nbr * 10 + (str[i] - '0');
+		i++;
+	}
+
+	return (nbr * sign);
+}