} // End function
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Function: recursEval *
* Input: ExpNode *
* Output: double *
* Description: A function that recursively traverse the expresssion*
* tree making the appropriate operations, and returns *
* the result. *
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
public double recursEval(ExpNode currNode)
{
if (currNode == null)
{
return(0);
}
else if (variables.ContainsKey(currNode.getValue()))
{
return(variables[currNode.getValue()]);
}
else
{
switch (currNode.getValue())
{
case "+":
{
return(recursEval(currNode.getLeftChild()) +
recursEval(currNode.getRightChild()));
}
break;
case "-":
{
return(recursEval(currNode.getLeftChild()) -
recursEval(currNode.getRightChild()));
}
break;
case "*":
{
return(recursEval(currNode.getLeftChild()) *
recursEval(currNode.getRightChild()));
}
break;
case "/":
{
return(recursEval(currNode.getLeftChild()) /
recursEval(currNode.getRightChild()));
}
break;
}
return(Double.Parse(currNode.getValue()));
}
} // End function
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Function: eval *
* Input: string *
* Output: double *
* Description: A function evaluates the operations in the tree, *
* by calling the recursive eval funcion. *
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
public double eval()
{
double result = 0;
if (root.getValue() == "")
{
Console.WriteLine("No expression tree exists!");
return(0);
}
else
{
return(result = recursEval(root)); // Calls recursive function
}
} // End function
