User defined floating point data type

Here, I am giving a user defined data-type class Double. this does not require any underlying floating point data-type as it works on the String data type


/*
hi,
check this out.
this program does not implement any underlying floating point data type.
this program just only works on the basic datatypes int_64, char and string
so it will avoid the different answers on different platform

*/

/* using string to store a double value */
//keeping significand and exponent in direct decimal format

#include <string>
#include <cstring>
#include <sstream>
#include <iostream>
using namespace std;

class Decimal
{
char sign;     
string significand; 
int64_t exponent;   

char ch;
string str;

public:
      void print() //check how to overload <<
      {
           int64_t val=0;
           string str="";
           string str1="";
           for(int64_t i=0;i<=exponent;i++)
  {
          ch=significand.at(i);
     val=10*val + (ch-48);
      }
     for(int64_t i=exponent+1;i<significand.length();i++)
     {
             str1=significand.at(i);
     str.append(str1);
     }
     if(sign=='+')
     {
                  if(str.length()>0)
cout<<val<<"."<<str; 
else
cout<<val;
}
else
{
    if(str.length()>0)
cout<<"-"<<val<<"."<<str;
else
cout<<"-"<<val;

}

}//end print function


       
       int64_t p(int64_t n,int64_t m)
 {
     int64_t res=1;
     for(int64_t i=0;i<m;i++)
     res=res*n;
    
     return res;
}
int64_t  to_int(string str)
{
         int64_t val=0;
         char ch;
 for(int64_t i=0;i<str.length();i++)
  {
          ch=str.at(i);
     val=10*val + (ch-48);
}
return val;
}



string to_string(int64_t n)
{
       int64_t temp=n;
       string temp1;
        while(temp>0)
     {
               ch=(temp%10)+48;
               str=ch;
               temp1.insert(0,str);
               temp=temp/10;
}
return temp1;
  }
 int64_t to_decimal(string str)
 {
        int64_t a;
        int64_t sum=0;
     for(int64_t i=0;i<str.length();i++)
     {
     a= (str.at(i))-48;
     sum+=(a*p(2,i));
     }
     return sum;
     }

void str_to_Decimal(string num)
{

int64_t zeros_just_after_decimal_point=0;
int64_t i=0;


if(num[0]!='-')
{

ch=num[0];
sign='+';
 if(num[0]=='+')
{
     sign='+';
    ch=num[1];
    i++;
}
}

    
else
{
    sign='-';
    ch=num[1];
    i++;
}


int64_t a=0;
int64_t b=0;




while(ch!='.'  && ch!='\0')
{
a= a*10+(ch-48);
ch=num[++i];   
}

if(ch!='\0')
{
ch=num[++i];

while(ch!='\0')
{
b=b*10+(ch-48);
if(b==0)
zeros_just_after_decimal_point++;

ch=num[++i]; 
}
}


string temp1,temp2,str;
int64_t temp=a,exp=0;
 while(temp>0)
     {
               ch=(temp%10)+48;
               exp++;
               str=ch;
               temp1.insert(0,str);
               temp=temp/10;
}

exponent=exp-1;

temp=b;
 while(temp>0)
     {
               ch=(temp%10)+48;
               exp++;
               str=ch;
               temp2.insert(0,str);
               temp=temp/10;
}
significand="";
significand.append(temp1);
for(i=0;i<zeros_just_after_decimal_point;i++)
{
                                             ch='0';str=ch;
   significand.append(str);
}   
                                            
significand.append(temp2);
}



Decimal operator+(Decimal d)
{
        /* this addition rounds to the exponent which is having greater value of exponent*/
    Decimal  res;
    res=Decimal();
   int64_t val1=0,val2=0;
//case 1 (if both signs are positive)
if(sign=='+' && d.sign=='+')
{
     res.sign='+';
     int64_t diff=0;
if(exponent>=(d.exponent))
{
                         res.exponent=exponent;
                         diff=exponent-(d.exponent);
                         d.exponent=exponent;
for(int64_t i=0;i<diff;i++)
{
        ch='0';str=ch;
   d.significand.insert(0,str);
}    
}//if exponent>d.exponent

else
{
                         res.exponent=d.exponent;
                         diff=(d.exponent)-exponent;
                         exponent=d.exponent;

for(int64_t i=0;i<diff;i++)
{
        ch='0';str=ch;
  significand.insert(0,str);
}    
}//else exponent>d.exponent

  for(int64_t i=0;i<=res.exponent;i++)
  {
          ch=significand.at(i);
     val1=10*val1 + (ch-48);
          ch=d.significand.at(i);  
              val2=10*val2 +  (ch-48);
}
int64_t val=val1+val2;
int64_t temp;
string  temp1,temp2;
temp=val;
 while(temp>0)
     {
               ch=(temp%10)+48;
               str=ch;
               temp1.insert(0,str);
               temp=temp/10;
}
val1=0; val2=0;

if(significand.length()<=d.significand.length())
{

    for(int64_t i=res.exponent+1;i<significand.length();i++)
{
     ch=significand.at(i);
     val1=10*val1 + (ch-48);
          ch=d.significand.at(i);  
              val2=10*val2 +  (ch-48);                                            

}
val=val1+val2;
temp=val;
int64_t exp=0;
 while(temp>0)
     {
               ch=(temp%10)+48;
               exp++;
               str=ch;
               temp2.insert(0,str);
               temp=temp/10;
}

if(exp>(significand.length()-exponent))
{
                     val=(to_int(temp1))+1;
                     temp1=to_string(val);
                     temp2.erase(0,1);
                     }              

res.significand=temp1+temp2;
}//if significand

else
{
    for(int64_t i=res.exponent+1;i<d.significand.length();i++)
{
     ch=significand.at(i);
     val1=10*val1 + (ch-48);
          ch=d.significand.at(i);  
              val2=10*val2 +  (ch-48);                                            

}
val=val1+val2;
temp=val;
int64_t exp=0;
 while(temp>0)
     {
               ch=(temp%10)+48;
               exp++;
               str=ch;
               temp2.insert(0,str);
               temp=temp/10;
}
if(exp>(d.significand.length()-res.exponent))
{
                     val=(to_int(temp1))+1;
                     temp1=to_string(val);
                     temp2.erase(0,1);
                     }              
res.significand=temp1+temp2;

}//else significand
 
}//if sign

return res;
}
};// class Decimal

int main()
{
    int64_t a,b,z;
    char ch='c';
    string str1,str2;
    Decimal obj1,obj2,obj3;
    obj1=Decimal();
    obj2=Decimal();obj3=Decimal();
   
    do{
    cout<<"\n welcome!!! please enter two positive floating point numbers. \n";
 
  cin>>str1;
  cin>>str2;
            obj1.str_to_Decimal(str1);
            obj2.str_to_Decimal(str2);
            //obj3.str_to_Decimal("-1831564.165");
           
            obj3=obj1+obj2;
           
            cout<<"\n";
            obj1.print();
            cout<<"+";
            obj2.print();
            cout<<"= ";
            obj3.print();
           
            cout<<"\n \n press e to exit and c to continue";
            cin>>ch;
}while(ch=='c');
return 0;
}