netpong/numeric_base.cpp

#include "includes/numeric_base.hpp"
#include <string>
#include <cmath>
#include <algorithm>

std::string possible_chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

unsigned int to_decimal(std::string num, int from_base) {
	char current_char = 0;
	int index = 0;
	unsigned int value = 0;

	/* Here, we convert 'num' to decimal (base 10) - Find the index of
	every character in the string, in 'possible_chars' and
	compute the value using  */
	for (int i=0; i < (int)num.length(); i++) {
		current_char = num.at(i);
		index = possible_chars.find(current_char);
		value += pow(from_base, num.length() - i - 1) * index;
	}

	return value;
}

/* Convert the given value from base 10 to the given base */
std::string from_decimal(unsigned int num, int to_base) {
	std::string return_val;
	int val = 0;
	/* Handle the special case of num being zero: In this case, the result is also zero */
	if (num == 0) {
		return_val = "0";
	} else {
		while (num > 0) {
			val = num % to_base;
			return_val.push_back(possible_chars[val]);
			num /= to_base;
		}
	}
	
	/* Reverse the string, since we started from the right */
	std::reverse(return_val.begin(), return_val.end());

	return return_val;
}

/* Convert the given value from 'from_base', to 'to_base' */
std::string base_convert(std::string num, int from_base, int to_base) {
	unsigned int temp = to_decimal(num, from_base);
	std::string result = from_decimal(temp, to_base);

	return result;
}