Question

I'm trying to convert between different number representations in C++ , I have the prototype but im not sure what do do from here

bool add(string & sum, bool & n, bool & z, bool & v, bool & c,

const string & term0, const string & term1);

term0 and term1 should each be 5-bit strings with each char being '0' or '1' – otherwise,

return false.

If term0 and term1 are ok, add's job is to perform the addition, putting the 5-bit result

in sum, put the resulting status bits in n, z, v, and c, and return true.

For example, add(s, n, z, v, c, "11110", "00011") should

set sum to "00001"

set n to false (result not negative)

set z to false (result not zero)

set v to false (2's complement representation isn't wrong)

set c to true (unsigned representation is wrong)

In determining v and c, here's a trick that might be helpful:

You can determine the values of v and c by looking at only the high-order bit of the

operands and result. For example

1

1000

0

1100

0

0100

looking at just the first bit:

2's complement has us adding neg plus non-neg equals non-neg; this is possible, so v is

set to false.

unsigned has us adding a big number and a little number, getting a little number; this is

impossible, so c is set to true.

Answer 1

Here is the required code in C++

#include<bits/stdc++.h>
using namespace std;

bool add(string & sum, bool & n, bool & z, bool & v, bool & c, const string & term0, const string & term1)
{
if(term0.size()!=5 || term1.size()!=5)
return false;
  
for(int i=0;i<5;i++)
{
if(term0[i]!='0' && term0[i]!='1')
return false;
if(term1[i]!='0' && term1[i]!='1')
return false;
}
  
sum="00000";
string str = sum;
int carry = 0;
for(int i = 4; i >= 0 ; i--)
{
int num0 = term0[i] - '0';
int num1 = term1[i] - '0';
  
sum[i] = ((num0 ^ num1) ^ carry)==0 ? '0' : '1'; // c is carry
carry = ((num0 & num1) | (num0 & carry)) | (num1 & carry);
}
  
n = (sum[0]=='1');
z = (sum == str);
v = (term0[0]==term1[0] && term0[0]!=sum[0]);
c = (carry==1);
return true;
}

int main()
{
string sum="";
string s1, s2;
bool n, z, v, c;
  
cout<<"Enter 1st 5-bit Binary Number: ";
cin>>s1;
cout<<"Enter 2nd 5-bit Binary Number: ";
cin>>s2;
  
cout<<endl;
if(add(sum, n, z, v, c, s1, s2))
{
cout<<"Sum is: "<<sum<<endl;
cout<<"Is Negative: "<<n<<endl;
cout<<"Is Zero: "<<z<<endl;
cout<<"Is 2's Complement representation wrong: "<<v<<endl;
cout<<"Is Unsigned representation wrong: "<<c<<endl;
}
else
cout<<"Invalid Inputs";
  
return 0;
}

Here is the Output for Sample Inputs: