dec2bin with stroke

dec2bin.cpp

// version 3, final
#include <iostream>
#include <string>
#include <vector>
#include <cstdlib> // atoi
#include <iomanip> // set, setfill
#include <cmath> // pow

using namespace std;

const int base = 1000 * 1000 * 1000;
int mult(vector<int> &a, int b) // mult long * short
{
	int carry = 0; // offset
	for (size_t i = 0; i < a.size() || carry; i++) 
	{
		if (i == a.size())
			a.push_back(0);
		long long cur = carry + a[i] * 1ll * b;
		a[i] = (int)(cur % base);
		carry = (int)(cur / base);
	}
	
	//while (a.size() > 1 && a.back() == 0)
	//	a.pop_back();
}

int intlen(int value)
{
  int len;
  for (len = 1; value > 9; len++)
  	value /= 10;
  return len;
}

void print(vector<int> &a)
{
	cout << (a.empty() ? 0 : a.back());
	for (int i = (int)a.size() - 2; i >= 0; i--)
		cout << setw(8) << setfill('0') << a[i];
	cout << endl;
}

int main() 
{
	cout << "Enter number:" << endl;
	string raw;
	cin >> raw;
	
	string out = "";
	cout << "Line length: " << raw.length() << endl;
	
	int count = 0; // digits before dot
	
	// part before dot
	cout << "Part before dot:" << endl;
	for (int i = 0; i < raw.length() && raw[i] != '.'; i++)
	{
		count++;
		char digit[5] = "0000";
		int temp = raw[i] - '0';
		for (int j = 0; j < 4; j++)
		{
			if (temp % 2 == 1)
				digit[3 - j] = '1';
			else digit[3 - j] = '0';
			temp /= 2;
		}
		cout << digit << endl;
		
		out += digit;
	}
	cout << "Result: " << out << "." << endl;
	
	
	// now read part after dot
	out += '.';
	cout << "Part after dot:" << endl;
	string s = raw.substr(count + 1, raw.length() - 1); // string after dot. not best solution for reading long int
	cout << "Length: " << s.length() << endl;
	vector<int> a;
	for (int i = (int)s.length(); i > 0; i -= 9)
		if (i < 9)
			a.push_back(atoi(s.substr(0, i).c_str())); 
		else
			a.push_back(atoi(s.substr(i - 9, 9).c_str())); // cutting blocks of 9
	
	// now convert part after dot
	int limit = 64; // max count of digits to convert
	print(a);
	for (int i = 0; i < limit; i++)
	{
		int len = (intlen(a[a.size() - 1]) == 9 ? 0 : intlen(a[a.size() - 1]));
		mult(a, 2);
		int newlen = intlen(a[a.size() - 1]);
		if (newlen - len == 1) // to remove first "bad" digit
			a[a.size() - 1] %= (int)(pow(10, newlen - 1));
		print(a);
		//cout << "Debug: " << newlen - len << endl;
		out += (char)(newlen - len + '0');
	}

	cout << out << endl;
	return 0;
}