This is one expression from the first line of the file.

- + + 4.0 - / - 22.0 2.0 5.0 * 3.0 4.0 7.0 / 6.0 3.0

The problem lies I do not understand where do these operands and numbers get stored to construct a expression tree during the time the above expression gets parsed. After constructing an expression tree, the tree is suppose to be able to output preorder,inorder and postorder expression of that tree.

From the example given, the operands are connected by an operator, but the example does not help guide me in terms of how to lay the operands and numbers out for this expression.

I tried using a stack diagram to visualize the design of my program better but I am stuck when 22.0 appears on the stack. What is suppose to happen when 22.0 appears on the stack?