.h
struct fraction {
public:
	fraction();
	fraction(signed int a, signed int b);
	fraction(signed int a);
	fraction(std::string s);
	double frac_eval();
	signed int numerator();
	signed int denominator();
	std::string str();
	std::string tex();
	fraction& operator +(fraction &a1);
	fraction& operator -(fraction &a1);
	fraction& operator *(fraction &a1);
	fraction& operator /(fraction &a1);
	fraction& operator +(int a1);
	fraction& operator -(int a1);
	fraction& operator *(int a1);
	fraction& operator /(int a1);
private:
	signed int top;
	signed int bot;
};





######################################################################################################################
.cpp
std::string fraction::str() {
	if (top == 0)
		return "0";
	else if (bot == 1)
		return std::to_string(top);
	else
		return boost::str(boost::format("%1%/%2%") % std::to_string(top) % std::to_string(bot));
}
std::string fraction::tex() {
	if (top == 0)
		return "0";
	else if (bot == 1)
		return std::to_string(top);
	else
		return boost::str(boost::format("\\frac{%1%}{%2%}") % std::to_string(top) % std::to_string(bot));
}
fraction::fraction(signed int a, signed int b) :top(a), bot(b) {}
fraction::fraction(signed int a) : top(a), bot(1) {}
fraction::fraction(std::string s) {
	size_t pos = s.find_first_of("/");
	top = std::stoi(s.substr(0, pos));
	if (pos == std::string::npos) bot = 1;
	else bot = std::stoi(s.substr(pos + 1, s.length()));
}
fraction::fraction() {}
double fraction::frac_eval() { return (double)top / (double)bot; }
signed int fraction::numerator() { return top; }
signed int fraction::denominator() { return bot; }
fraction& fraction::operator+(fraction &a1) {
	top = a1.numerator()*bot + a1.denominator()*top;
	bot = a1.denominator()*bot;
	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}
fraction& fraction::operator-(fraction &a1) {
	top = -a1.numerator()*bot + a1.denominator()*top;
	bot = a1.denominator()*bot;
	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}
fraction& fraction::operator*(fraction &a1) {
	top = a1.numerator()*top;
	bot = a1.denominator()*bot;
	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}
fraction& fraction::operator/(fraction &a1) {
	bot = a1.numerator()*bot;
	top = a1.denominator()*top;
	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}

fraction & fraction::operator+(int a1)
{
	top = a1*bot +top;

	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}

fraction & fraction::operator-(int a1)
{
	top = -a1*bot + top;

	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}

fraction & fraction::operator*(int a1)
{
	top = a1*top;

	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}

fraction & fraction::operator/(int a1)
{
	bot = a1*bot;

	for (int i = abs(top*bot); i > 1; i--) {
		if ((top % i == 0) && (bot % i == 0)) {
			bot /= i;
			top /= i;
		}
	}
	return *this;
}