// A method to add the binary numbers obtained previously.
public string addition(string first, string second)
{
// A string to store the result.
string result = "";
SameSize ss = new SameSize();
// A method to ensure both the strings are of equal length.
int length = ss.makeEqualLength(ref first, ref second);
// A carry bit.
int carry = 0;
for (int i = length - 1; i >= 0; i--)
{
int firstBit = first[i] - '0';
// Retrieves individual bits.
int secondBit = second[i] - '0';
// Exclusive-OR Operation to perform Addition.
int sum = (firstBit ^ secondBit ^ carry) + '0';
// Exclusive-OR Operation to perform Addition.
// Retrieves character representaion of sum.
result = (char)sum + result;
carry = (firstBit & secondBit) | (secondBit & carry) | (firstBit & carry);
}
if (carry > 0)
{
// Appends 1 if carry bit is present at the end of traversal.
result = '1' + result;
}
// Sends back the sum obtained.
return(result);
}
public string subtraction(string first, string second)
{
SameSize ss = new SameSize();
// A string To find The 2's complement.
string compSecond = "";
// A result string to store and return the computed difference.
string result = "";
// References(pointers) of the strings are sent to balance their lengths by appending 0's at the beginning of the string which is smaller in length.
int length = ss.makeEqualLength(ref first, ref second);
for (int i = 0; i <= length - 1; i++)
{
if (second[i] == '1')
{
// Finding 1's complement of the number by replacing 1 with 0 and 0 with 1.
compSecond = compSecond + '0';
}
else
{
compSecond = compSecond + '1';
}
}
// A string to add 1's complement by 1 to make it a 2's complement.
string One = "1";
// Addition method is reused to add 1 to 1's complement. The obtained result is a 2's complement.
compSecond = addition(compSecond, One);
// Performing Exclusive-OR between 2's complement of a string and another string gives the difference
result = addition(first, compSecond);
// First Character is the Overflow Digit occured by 2's complement and hence should be removed...
result = result.Remove(0, 1);
// The subtracted result is returned.
return(result);
}