#include <iostream>
#include <stdio.h>
using namespace std;

const int MAX_CAP=10;

/* Display an big integers stored as an array of decimal digits
   bigInt[0] is 1-th digit
   bigInt[1] is 10-th digit
    ...
   the number of digits is given by len
*/
void Display(int bigInt[], int len)
{
   //todo by you. You need to display the most-significant digit first, and 1-th digit last 

}

/* Add two large integers and store the result in res 
  aDigits and aLen give the first integer, bDigits and bLen give the second integer
  sumDigits and sumLen will store the sum
  return true fi successful; false if fail (due to overflow) 
  */
bool AddLargeInt (int aDigits[], int aLen, int bDigits[], int bLen,
	int sumDigits[], int & sumLen)
{
	//Todo by you
	//1. Pad the two operands with leading 0's, i.e., add 0's to the end of 
	// aDigits, bDigits array 


	int carry=0; 
	//2. adding the two large integers, below is the pseudocode 
	// for i=0 to MAX_CAP-1  //start from 1-th digit, 10-th digit, ... 
	//     add the aDigits[i], bDigits[i] and carry up, and set to sum 
	//     set carry to 1 if the above sum is >=10 
	//     set sum[i] to sum-carry 

	//if carry!=0
	//   overflow, return false
	//otherwise 
	//   return true
	return true; //for now 

}

/* Read large integers of up to MAX digits, store the digits in the array, and set the 
   digit len
   return true if the input is valid, false if otherwise
   */
bool ReadLargeInt (int digits[], int & digit_len)
{
	string input;
	int dig_value;

	cout <<"Enter large int (up to "<<MAX_CAP <<"  digits):";
	cin >> input;
	//cout <<"You enter:"<<input<<endl;

	digit_len = input.length(); //call the method on string class to get the length of input
	if (digit_len>100)
	{
		cout <<"The input is too long\n";
		return false;
	}

	for (int i=0;i<digit_len;i++)
	{
		dig_value = input[digit_len-i-1]-'0'; //convert char to int value
		            //scan input string from the end to the front 
			    // when i=0, input[digit_len-1] is accessed, converted to 0,1..9
			    // when i=1, input[digit_len-2] .... 

		if (dig_value>9 || dig_value<0)
		{
			cout <<"Invalid char " << input[digit_len-i-1]<< " in the input"<<endl;
			return false;
		}
		digits[i]=dig_value;
	}
	return true;
}

int main()
{
   int num[MAX_CAP]={0,0,0,0,0,5,4,8,9};
   int num_len=9;

   int num2[MAX_CAP]={1,0,0,5,0,1};
   int num_len2=6;

   //Test Display() function
   Display(num,num_len);
   cout <<"+";
   Display(num2,num_len2);

   //Test AddBigInt ... 


   //Test ReadLargeInt ... 
   bool ret;
   do{
   	ret = ReadLargeInt (num, num_len);
   } while (!ret);

   cout <<"Read this:";
   Display (num, num_len);

   
   //Todo: 
   //Main loop that allows user to enter two large ints, display the sum 

}