Question

Why does my code print nothing in cout? I think my class functions are incorrect but I don't see why.

bigint.h:

#include <string>
#include <vector>

class BigInt {
private:
   int m_Input, m_Temp;
   std::string m_String = "";
   std::vector<int> m_BigInt;
public:
   BigInt(std::string s)   // convert string to BigInt
   {
       m_Input = std::stoi(s);
       while (m_Input != 0)
       {
           m_Temp = m_Input % 10;
           m_BigInt.push_back(m_Temp);
           m_Input %= 10;
       }

   }
   std::string to_string() // get string representation
   {
       for (auto digit : m_BigInt)
       {
           m_String += std::to_string(digit);
       }
       return m_String;
   }

   void add(BigInt b) // add another BigInt to this one
   {
       for (int digit = 0; digit != b.getVect().size(); digit++)
       {
           this->getVect()[digit] += b.getVect()[digit];
       }
   }

   std::vector<int> getVect() // get BigInt vector
   {
       return m_BigInt;
   }
};

test1.cpp:

#include "bigint.h"
#include
using namespace std;

int main() {
   BigInt a("13");
   BigInt b("42");
   b.add(a);    // increase b by a
   cout << b.to_string() << endl; // prints 55
   b.add(a);    // increase b by a
   cout << b.to_string() << endl; // prints 68
}

Answer 1

In case of any query do comment. Please rate answer as well. Thanks

Note: there were few problems in the program, but still you require to change add function to handle carry in addition. Other thing was when you were trying to find a digit to put it in bigInt vector, it was running infinitely as you were not dividing the digit by 10 to get next digit. This is corrected and also when you convert vector to string you have to use reverse iterator because you are pushing digits to the back.

Code:

#include <string>
#include <vector>

class BigInt {
private:
   int m_Input, m_Temp;
   std::string m_String = "";
   std::vector<int> m_BigInt;
public:
   BigInt(std::string s)   // convert string to BigInt
   {
       m_Input = std::stoi(s);
       while (m_Input != 0)
       {
           m_Temp = m_Input % 10;
           m_BigInt.push_back(m_Temp);           
           m_Input /= 10;
       }

   }
   std::string to_string() // get string representation
   {
       //clear the m_String every time when your print
       m_String ="";
       //you need to reverse iterate the vector
       for (auto it = m_BigInt.rbegin(); it != m_BigInt.rend(); it++) 
       {
           m_String += std::to_string(*it);
       }
       return m_String;
   }


   void add(BigInt b) // add another BigInt to this one
   {
       for (int digit = 0; digit != b.getVect().size(); digit++)
       {
           m_BigInt[digit] += b.getVect()[digit];
       }
   }


   std::vector<int> getVect() // get BigInt vector
   {
       return m_BigInt;
   }
};

=============difference in code=======

output: