Define a class which implements arithmetic with arbitrary precision

[svatstika]

Hi everyone!
I'm reading a book and doing some exercises in this book. One of them is: define a class, which implements arithmetic (+, -, /, *) with arbitrary precision. This is a new type with just some arithmetic operations. With type double we also can do some arithmetic but with a definite precision.
May someone get me started. I need an idea to get into.
Thanks in advanced!

[alexchen]

This might help.

int max(int a, int b){

	return a>b ? a:b;

}
int min(int a, int b){

	return a<b ? a:b;

}

Upvote my post if they helped.

[alexchen]

If you want to read a line.

void line(char*Filename,int maxline){

	ifstream file;
	file.open(Filename);

	string input,output;


	for(int x = 0; x < maxline; x++) 
	{
	getline(file,input);
	
	output += string(input + "\n");

	}
	cout<<output<<endl;
}

[alexchen]

If you are using geometry.

[mrnutty]

First you need to be able to represent data in arbitrary length. One way to do that is use a std::vector<int> numbers or even std::string. Personally, I would choose the std::strings, because its easier to work with.

So lets define such a type :

class Number{
 private:
 std::string _numbers;
 public:
 Number(){}
 Number(const std::string& num) : _numbers(num){}
};

Now you need to define the operator interface, you can either use overloaded operators or member functions. I would suggest you to have private member function and implement the overloaded operators like so :

class Number{
private:
 std::string _numbers;
public:
 Number(){}
 Number(const std::string& num) : _numbers(num){}
 //add operator
 std::string operator+(const std::string& rhsNumber)const{ return _add(rhsNumber);}
 //subtract operator
 std::string operator-(const std::string& rhsNumber)const{return _add(-rhsNumber);}
 //divide operator
 std::string operator/(const std::string& rhsNumber)const{return _divide(rhsNumber);}
 //multiply operator
 std::string operator*(const std::string& rhsNumber)const{return _multiply(rhsNumber);}
 //negation operator
 std::string operator-()const;
private:
 //helper function
 string _add(std::string rhsNumber)const{/*add logic here */}
 string _multiply(std::string rhsNumber)const{/*add logic here */}
 string _divide(std::string rhsNumber)const{/*add logic here */}
};

[svatstika]

The thing is: to implement arithmetic, we need to convert rhsNumber._numbers to type double (for example atof(rhsNumber)) and then work with them. And as I said at the first post. With two number type double we only can implement arithmetic with a define precesion.

string Number::_add(std::string rhsNumber)const{
      /*add logic here */
      return atof(this->_numbers) + atof(rhsNumber._numbers);
}

What am I thinking is correct?

[mrnutty]

No the point is to work with each digit in the string, not convert the string into a double..

[svatstika]

Ok so do you mean that: we have the thing with the algorithm of addition 2 numbers that we've already know from first or second class at school?