public static BigInt Substract(BigInt number1, BigInt number2)
{
bool ResIsNegative = number1.IsNegative;
if (number1.isNegative && !number2.IsNegative)//-+
{
return(Sum(number1, new BigInt(number2.number, !number2.IsNegative)));
}
if (!number1.isNegative && number2.IsNegative)//+-
{
return(Sum(number1, new BigInt(number2.number, !number2.IsNegative)));
}
int length = number1.number.Length;
if (number1.number.Length < number2.number.Length)
{
length = number2.number.Length;
}
StringBuilder sbNum1 = new StringBuilder();
for (int i = 0; i < length; i++)
{
try
{
sbNum1.Append(number1.number[number1.number.Length - i - 1]);
}
catch
{
sbNum1.Append("0");
}
}
StringBuilder sbNum2 = new StringBuilder();
for (int i = 0; i < length; i++)
{
try
{
sbNum2.Append(number2.number[number2.number.Length - i - 1]);
}
catch
{
sbNum2.Append("0");
}
}
if (!FirstBigger(number1, number2))
{
StringBuilder sbSwap = sbNum1;
sbNum1 = sbNum2;
sbNum2 = sbSwap;
//ako 2roto e po golqmo, se obrushta znaka!!!
ResIsNegative = !ResIsNegative;
}
string ResNumber;
int curr1;
int curr2;
int curr;
int NaUm = 0;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++)
{
try
{
curr1 = int.Parse(sbNum1[i].ToString());
}
catch
{
curr1 = 0;
}
try
{
curr2 = int.Parse(sbNum2[i].ToString());
}
catch
{
curr2 = 0;
}
curr = (curr1 - curr2 - NaUm);
NaUm = 0;
if (curr < 0)
{
curr += 10;
NaUm = 1;
}
sb.Append(curr.ToString());
}
StringBuilder sbReverse = new StringBuilder();
for (int i = sb.Length - 1; i >= 0; i--)
{
sbReverse.Append(sb[i]);
}
ResNumber = sbReverse.ToString();
return(new BigInt(ResNumber, ResIsNegative));
}