atoibase.c

// Assignment name  : ft_atoi_base
// Expected files   : ft_atoi_base.c
// Allowed functions: None
// --------------------------------------------------------------------------------

// Write a function that converts the string argument str (base N <= 16)
// to an integer (base 10) and returns it.

// The characters recognized in the input are: 0123456789abcdef
// Those are, of course, to be trimmed according to the requested base. For
// example, base 4 recognizes "0123" and base 16 recognizes "0123456789abcdef".

// Uppercase letters must also be recognized: "12fdb3" is the same as "12FDB3".

// Minus signs ('-') are interpreted only if they are the first character of the
// string.

// Your function must be declared as follows:

// int	ft_atoi_base(const char *str, int str_base);


#include <stdio.h>

int ft_strlen(char *str)
{
	int i = 0;
	while(str[i])
		i++;
	return(i);
}

int	ft_atoi_base(const char *s, int str_base)
{
	int sign = 1;
	int res = 0;
	int i = 0;
	char *str;
	str = (char *)s;

	if(str[i++] == '-')
		sign = -sign;
	while(str[i])
	{
		if(str[i] >= '0' && str[i] <= '9')
			res = res * str_base + (str[i] - '0');
		if(str[i] >= 'A' && str[i] <= 'F')
			res = res * str_base + (str[i] - 55);
		if(str[i] >= 'a' && str[i] <= 'f')
			res = res * str_base + (str[i] - 87);
		i++;
	}
	return(sign * res);
}

int main()
{
	char *res = "-1AD256F";
	printf("%d", ft_atoi_base(res, 16));
}