Question

public override Models.CalculationNode Parse(string expression)
{
    var calNode = new Models.CalculationNode();

    int i = expression.Length;
    char[] x = expression.ToCharArray();
    string temp = "";

    //Backwards assembly of the tree

    //Right Node
    while (!IsOperator(x[i]) && i > 0)
    {
        if (!x[i].Equals(' ')) temp = x[i] + temp;
        i--;
    }
}

It has been a while since I’ve used trees and I’m getting an out of bounds exception in the while loop.

Answer 1

You’ve got an off-by-1 error when you start at i = expression.Length. That first index will be out of bounds right off the bat. You could rewrite the loop as a for loop like so:

char[] x = expression.ToCharArray();
string temp = "";

//Backwards assembly of the tree

//Right Node
for (int i = x.Length - 1; i >= 0 && !IsOperator(x[i]); --i)
{
    if (!x[i].Equals(' ')) temp = x[i] + temp;
}