Data structure class please help 16 In C++, the largest int value is 214748 3647

Question

Data structure class please help

16 In C++, the largest int value is 214748 3647. So an integer larger than this cannotbe stored and processed as an integer. Similarly, if the sum or product of two positive integers is greater than 2147483647, the result will be incorrect. One way to store and manipulate large integers is to store each individual digit of the number in an array. Design the class largeIntegers so that an object of this class can store an integer up to 100 digits long. Overload the operators+ and to add and subtract, respectively, the values of two objects of this class. (In the Programming Exercises in Chapter 3, we will overload the multiplication operator.) Overload the assignment operator to copy the value of a large integer into another large integer. Overload the stream extraction and inserion operators for easy input and output. Your program must contain appropriate constructors to initialize objects of the class largeIntegers. (Hint: Read numbers as strings and store the digits of the number in the reverse order. Add instance variables to store the number of digits and the sign of the number.)

Explanation / Answer

#include <iostream>
#include <cctype>
#include <cstring>
using namespace std;
#define DIGITS 100
class largeintegers
{
public:
largeintegers();
void Input();
void Output();
largeintegers operator+( largeintegers );
largeintegers operator-( largeintegers );
largeintegers operator*( largeintegers );
int operator==( largeintegers);
private:
int integer[ DIGITS ];
int len;
};
void largeintegers::Output()
{
int i;
for (i=len-1;i >= 0; i-- )
cout<<integer[i];
}
void largeintegers::Input()
{string in;
int i,j,k;
cout<<"Enter a number("<<DIGITS<<" digits max):";
cin>>in;
for(i=0;in[i]!='';i++);
len=i;
k=0;
for(j=i-1;j>=0;j--)
    integer[j]=in[k++]-48;
}
largeintegers::largeintegers( )
{
for ( int i = 0; i <DIGITS; i++ )
      integer[ i ] = 0;
len=DIGITS-1;
}
int largeintegers::operator==( largeintegers op2 )
{int i;
if(len<op2.len)
      return -1;
if(op2.len<len)
      return 1;
for(i=len-1;i>=0;i--)
      if(integer[i]<op2.integer[i])
           return -1;
       else if(op2.integer[i]<integer[i])
             return 1;
return 0;
}
largeintegers largeintegers::operator+( largeintegers op2 )
{largeintegers temp;
int carry = 0;
int c,i;
if(len>op2.len)
    c=len;
else
    c=op2.len;


for ( i=0; i<c; i++ )
     {temp.integer[ i ] =integer[ i ] + op2.integer[ i ] + carry;
     if ( temp.integer[ i ] > 9 )
         {temp.integer[ i ] %= 10;
          carry = 1;
         }
     else
          carry = 0;
     }
if(carry==1)
    {temp.len=c+1;
    if(temp.len>=DIGITS)
          cout<<"***OVERFLOW***** ";
    else
         temp.integer[i]=carry;
   
    }
else    
   temp.len=c;
return temp;
}
largeintegers largeintegers::operator-( largeintegers op2 )
{largeintegers temp;
int c;
if(len>op2.len)
    c=len;
else
    c=op2.len;
int borrow = 0;
for( int i = c;i >= 0;i--)
if(borrow==0)
    {if(integer[i]>=op2.integer[i])
           temp.integer[i]=integer[i]-op2.integer[i];
    else
          {borrow=1;
          temp.integer[i]=integer[i]+10-op2.integer[i];
          }
    }
else
    {borrow=0;
    if(integer[i]-1>=op2.integer[i])
           temp.integer[i]=integer[i]-1-op2.integer[i];
      else
          {borrow=1;
          temp.integer[i]=integer[i]-1+10-op2.integer[i];
          }
      }
temp.len=c;
return temp;
}   
largeintegers largeintegers::operator*( largeintegers op2 )
    { largeintegers temp;
      int i,j,k,tmp,m=0;
       for (int i=0; i<op2.len; i++)
        { k=i;
        for (j=0; j< len; j++)
           {tmp = integer[ j ] * op2.integer[i];
            temp.integer[k] =temp.integer[k]+tmp;
            temp.integer[k+1] =temp.integer[k+1]+ temp.integer[k]/10;
            temp.integer[k] %=10;
            k++;
            if(k>m)
                m=k;
                }
        }
        temp.len=m;
         if(temp.len>DIGITS)
          cout<<"***OVERFLOW***** ";
        return temp;
    }


using namespace std;
int main()
{int c;
largeintegers n1,n2,result;
n1.Input();
n2.Input();
n1.Output();
cout <<" + ";
n2.Output();
result=n1+n2;
cout<< " = " ;
result.Output();
cout << " ";
n1.Output();
cout <<" - ";
n2.Output();
result=n1-n2;
cout<< " = " ;
result.Output();
cout << " ";
n1.Output();
cout <<" * ";
n2.Output();
result=n1*n2;
cout<< " = " ;
result.Output();
cout << " ";
c=n1==n2;
n1.Output();
switch (c)
{case -1: cout<<" is less than ";
            break;
   case 0: cout<<" is equal to ";
            break;
    case 1: cout<<" is greater than ";
            break;
    }  
n2.Output();
cout << " ";                
system("pause");
}

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