public void undo()
{
if (OperationDisplay != "")
{
OperationDisplay = OperationDisplay.Remove(OperationDisplay.Length - 1);
}
int openingBrackets = 0;
int closingBrackets = 0;
for (int i = 0; i < OperationDisplay.Length; i++)
{
if (OperationDisplay[i] == '(')
{
openingBrackets++;
}
if (OperationDisplay[i] == ')')
{
closingBrackets++;
}
}
if (openingBrackets > closingBrackets)
{
string x = OperationDisplay.Substring(OperationDisplay.LastIndexOf('('));
x = x.Trim('(');
x = x.Trim('-');
OperationDisplay = OperationDisplay.Remove(OperationDisplay.LastIndexOf('('));
OperationDisplay += x;
}
}
public void signChange()
{
bool anyOperators = false;
bool positiveSign = true;
int index = 0;
string x = "";
if (OperationDisplay.Length != 0 && !(OperationDisplay.LastIndexOfAny(operators.ToArray()) == OperationDisplay.Length - 1))
{
for (int i = 0; i < 4; i++)
{
if (OperationDisplay.Contains(operators[i]))
{
anyOperators = true;
}
}
if (anyOperators)
{
index = OperationDisplay.LastIndexOfAny(operators.ToArray());
}
if (anyOperators && OperationDisplay.Substring(index - 1).Contains('('))
{
positiveSign = false;
}
if (positiveSign)
{
if (index != 0)
{
x = OperationDisplay.Substring(index + 1);
}
else
{
x = OperationDisplay;
}
x = "(-" + x + ')';
if (index != 0)
{
OperationDisplay = OperationDisplay.Remove(index + 1);
OperationDisplay += x;
}
else
{
OperationDisplay = x;
}
}
else
{
x = OperationDisplay.Substring(index - 1);
x = x.Trim('(', ')');
x = x.Trim('-');
OperationDisplay = OperationDisplay.Remove(index - 1);
OperationDisplay += x;
}
}
}
