}//End of Operand class
//Actual tree construction from the expression
private OperandClass BuildTreeOperand()
{
OperandClass tree = null;
string expression = AnsBox.Text;
if (!char.IsNumber(expression.Last()))
{
expression = expression.Substring(0, expression.Length - 1);
}
string numberStr = string.Empty;
foreach (char c in expression.ToCharArray())
{
if (char.IsNumber(c) || c == '.' || numberStr == string.Empty && c == '-')
{
numberStr += c;
}
else
{
AddOperandToTree(ref tree, new OperandClass()
{
value = double.Parse(numberStr)
});
numberStr = string.Empty;
Operands op = Operands.MINUS; //Set default case
switch (c)
{
case '-': op = Operands.MINUS; break;
case '+': op = Operands.PLUS; break;
case '/': op = Operands.DIV; break;
case 'x': op = Operands.TIMES; break;
}
AddOperandToTree(ref tree, new OperandClass()
{
opp = op
});
}
}
//Last number
AddOperandToTree(ref tree, new OperandClass {
value = double.Parse(numberStr)
});
return(tree);
}
//Display results
private void Eqbtn_Click(object sender, RoutedEventArgs e)
{
//Qualify input
if (string.IsNullOrEmpty(AnsBox.Text))
{
return;
}
OperandClass tree = BuildTreeOperand();
double value = CalcTree(tree);
AnsBox.Text = value.ToString();
}
private void AddOperandToTree(ref OperandClass tree, OperandClass elem)
{
if (tree == null)
{
tree = elem;
}
else
{
if (elem.opp < tree.opp)
{
OperandClass auxTree = tree;
tree = elem;
elem.left = auxTree;
}
else
{
AddOperandToTree(ref tree.right, elem);// recursion used to loop through operands
}
}
}
private double CalcTree(OperandClass tree)
{
if (tree.left == null && tree.right == null)
{
return(tree.value);
}
else //its an operation
{
double subResult = 0;
switch (tree.opp)
{
case Operands.MINUS: subResult = CalcTree(tree.left) - CalcTree(tree.right); break;
case Operands.PLUS: subResult = CalcTree(tree.left) + CalcTree(tree.right); break;
case Operands.DIV: subResult = CalcTree(tree.left) / CalcTree(tree.right); break;
case Operands.TIMES: subResult = CalcTree(tree.left) * CalcTree(tree.right); break;
}
return(subResult);
}
}
