public static big operator -(big lhs, big rhs)
{
var isLeftPositive = lhs.Sign == Sign.Positive;
var isRightPositive = rhs.Sign == Sign.Positive;
// +5 - +3 = +(+5 - +3)
if (isLeftPositive && isRightPositive)
{
return(BigIntMath.Subtract(lhs, rhs));
}
// -5 - -3 = -5 + 3 = +(-5 + +3)
if (!isLeftPositive && !isRightPositive)
{
return(BigIntMath.Add(lhs, -rhs));
}
// 5 - -3 = 5 + 3 = +(+5 + +3)
if (isLeftPositive)
{
return(BigIntMath.Add(lhs, -rhs));
}
// -5 - +3 = -5 - 3 = -(5 + 3) = -(+5 + +3)
return(-BigIntMath.Add(-lhs, rhs));
}
public static big operator --(big bigInt) => BigIntMath.Subtract(bigInt, big.One);