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+--- Thread: [Java] Class Hierarchy Design - Serious Help Needed! (/showthread.php?tid=7917)
[Java] Class Hierarchy Design - Serious Help Needed! - Conciente - 2009-02-02
This one... I have NO CLUE how to even start. I hate the teacher because he doesn't want us to ask any questions to him so I'm back here requesting help.
Design a class hierarchy that allows to determine the type of result of an expression following the precedence and combination rules of the C language. The expression is to be supplied as a String using, instead of variables, the type corresponding to each one of them.
For example, assuming the following group of declarations and expression:
int a;
float b;
char c;
b= a / c + (c + 25)
the corresponding String would be supplied as:
float = int / char + (char + int)
resulting in a float.
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*lost*
[Java] Class Hierarchy Design - Serious Help Needed! - Spaz - 2009-02-02
This is a classic problem, although the more typical form is to evaluate a numeric expression without any variables.
1. Parse the expression into tokens.
2. Convert from infix to postfix.
3. Evaluate.
Google is your friend if any of those steps confuse you.
[Java] Class Hierarchy Design - Serious Help Needed! - GummyBear - 2009-02-02
Its a basic parsing problem. What you need is a tokenizer to break the string into "tokens", a parser to parse the string for correct syntax and objects creation. The class hierachy should be something like this:
basic
class Char
class Int
class Float
expressions
class Add
class Divide
class Bracket
As you can see, Add and Divide take in 2 arguments, Bracket takes 1, etc. The rest you should learn for yourself.