binary_user_literal.cpp

#include <iostream>
#include <cassert>

unsigned operator"" _b(const char *str)
{
    unsigned ret = 0;
	for(size_t i = 0; i < str[i] != '\0'; ++i) {
		char digit = str[i];
		assert(digit == '0' || digit == '1' && "Binary literal's only support 0 or 1");
		ret = ret * 2 + (digit - '0');
	}
	return ret;
}

int main() {
	auto binary_literal = 0101_b;
	std::cout << binary_literal << "\n";
}