Print large powers of 2

pow2.cpp

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdint>

using namespace std;

using Digit = uint8_t;
using BigInt = vector<Digit>;

void doubleint(BigInt& num) {
	Digit carry = 0;
	for (int i = 0; i < num.size(); i++) {
		Digit digit = num[i];
		digit = digit * 2 + carry;

		carry = digit / 10;
		digit = digit % 10;

		num[i] = digit;
	}

	if (carry > 0) {
		num.push_back(carry);
	}
}

void printint(const BigInt& num) {
	for (int i = num.size() - 1; i >= 0; i--) {
		cout << (int)num[i];
	}
}

int main(int argc, char** argv) {
	if (argc < 2) {
		return 0;
	}
	int n = atoi(argv[1]);

	BigInt num {1};

	for (int i = 0; i < n; i++) {
		doubleint(num);
	}

	printint(num);
	cout << "\n";

	return 0;
}