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Computer Science Canada

recursive function problem

Author:

efus [ Sun Nov 30, 2008 3:44 pm ]

Post subject:

recursive function problem

Hi, I am having some troubles with a recursive function.
The function needs to get a string as an input. The string contains both symbols and numbers. What the function does is doing some operation on the two children of a node, the node being the operation(+,-,*,/).
The thing is, I need the function to return a double. This couses a problem since I cant just convert the string to a double becouse of the operators.
This is the algoritm:

code:

function Evaluate {
if node is an operator(+,-,*,/) then
evaluate the right and left child
apply the operator of the node to the two children
else if the node is a value then
the result is the value

Author:	Tony [ Sun Nov 30, 2008 3:52 pm ]
Post subject:	RE:recursive function problem
typecast the value to Double. Then you are always doing operations on two Double's, so you can just return the same type. It doesn't make sense to convert a String, since "+" in Double is meaningless.

Author:	Vermette [ Sun Nov 30, 2008 6:18 pm ]
Post subject:	RE:recursive function problem
In case you're not sure what Tony is referring to: http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Double.html Make note of the valueOf(String s) method.

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