Asked By
Sharon
230 points
N/A
Posted on - 05/15/2011
Hi there,
I am learning coding in C++. I would like to start, by making a full functional calculator. All of them are pretty done but I want some more options which are present in a scientific calculator, like binary calculation. I don't see any function for this. So I guess I have to make one.
I have been trying to add the binary to decimal conversion. I know that the basic process is:
But how do I take the digits 1 at a time. Should I take the binary number as a string or by integer? Please help.
Finding Decimal Equivalent of a Binary Number
Sharon,
You don't need to use String as long as you are just considering binary and decimal ( the digits are within 0-9) . You can use a integer.
To fetch the last digit. Use:
lastIDig=n%10;
and then when done calculation of the last digit. You can delete the last digit by simple integer division.
n/=10;
Hope this helps.
Answered By
Sharon
230 points
N/A
#95506
Finding Decimal Equivalent of a Binary Number
Thank you very much.
But how do I know, how many digits are there in the number? Shall I fix it to be some where around 12 digit, by 0 padding to the left?
I am doing something like:
for(digit=1;digit<=numberofdigits;digit++)
   {
       result+=(n%10)*mult;
       mult*=2;
       n/=10;
   }
Finding Decimal Equivalent of a Binary Number
You don't actually need to know the number of digits. Since you are dividing n by the base every time. It will eventually know when the conversion is done, by monitoring n( it would be 0 when done).
while(n>0)
   {
       result+=(n%10)*mult;
       mult*=2;
       n/=10;
   }
Answered By
Sharon
230 points
N/A
#95510
Finding Decimal Equivalent of a Binary Number
Thanks a lot. That was a pretty clean solution. So here are my 2 functions.
int binary_to_decimal(int n)
{
   int result=0,mult=1;
   while(n>0)
   {
       result+=(n%10)*mult;
       mult*=2;
       n/=10;
   }
   return result;
}
and
 int from_decimal_to_binary(int n)
   {
       int result=0,mult=1;
       while(n>0)
       {
           result+=(n%2)*mult;
           mult*=10;
           n/=2;
           }
           return result;
       }
Tell me if I can make any more upgrade.
Finding Decimal Equivalent of a Binary Number
You are welcome.
Anyway you can extend this function to be much more generalized. For example this is the 2 generalized functions of yours:
int to_decimal(int n,int b)
{
   int result=0,mult=1;
   while(n>0)
   {
       result+=(n%10)*mult;
       mult*=b;
       n/=10;
   }
   return result;
}
 int from_decimal(int n,int b)
   {
       int result=0,mult=1;
       while(n>0)
       {
           result+=(n%b)*mult;
           mult*=10;
           n/=b;
           }
           return result;
       }
They act almost same as yours. Â I am just passing the base here as a parameter. So it is capable of handling any base conversion ( base smaller than 10). Â If you want to do a decimal to binary just issue:
from_decimal(n,2);Â Â Â Â // 2 is the base for binary
for octal
from_decimal(n,8);Â Â Â Â // same function with base 8.
Answered By
Sharon
230 points
N/A
#95513
Finding Decimal Equivalent of a Binary Number
That was freaking awesome!! Â Thank you very much.
