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Groups > comp.lang.java.programmer > #19333

Re: Operation in String to Double conversion

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On Sun, 14 Oct 2012 12:39:18 -0700, William Lopes wrote:

> Hi guys!
> 
> So, I have to do a conversion between String and Double object, but my
> string is a mathematical operation like "100 + 10". Even when I make a
> conversion using NumberFormat.getInstance of "100 + 10", my result is
> 100.0 only.
> 
> I would like to do it without split my string of way manually.
>
Sounds like you need an mathematical expression parser. I don't think 
there's anything suitable in the standard classes. You can:

1)see if there's a third party mathematical expression parser available

2)use a compiler generator like Coco/R 
  http://www.ssw.uni-linz.ac.at/Research/Projects/Coco/
  to create one.

3)attempt to roll your own from scratch.

If it was my problem I'd work down that list in the order shown unless 
there are constraints set, i.e. its an assignment that you are required 
to solve by yourself.

I've used Coco/R to generate an equivalent Java class that could handle 
the sort of expressions used in C preprocessor commands: it was dead easy 
once I understood how Coco/R works, but then again I had previously 
solved non-trivial problems with lex and yacc.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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Thread

Operation in String to Double conversion William Lopes <williamlopes.dev@gmail.com> - 2012-10-14 12:39 -0700
  Re: Operation in String to Double conversion Martin Gregorie <martin@address-in-sig.invalid> - 2012-10-14 20:32 +0000
    Re: Operation in String to Double conversion William Lopes <williamlopes.dev@gmail.com> - 2012-10-14 14:08 -0700
      Re: Operation in String to Double conversion markspace <-@.> - 2012-10-14 15:59 -0700
        Re: Operation in String to Double conversion William Lopes <williamlopes.dev@gmail.com> - 2012-10-14 17:45 -0700
        Re: Operation in String to Double conversion frank.asseg@gmail.com - 2012-10-15 11:18 -0700
          Re: Operation in String to Double conversion Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-10-16 00:14 +0200
            Re: Operation in String to Double conversion frank.asseg@gmail.com - 2012-10-15 15:41 -0700
        Re: Operation in String to Double conversion frank.asseg@gmail.com - 2012-10-15 11:27 -0700
          Re: Operation in String to Double conversion Lew <lewbloch@gmail.com> - 2012-10-15 12:40 -0700
            Re: Operation in String to Double conversion frank.asseg@gmail.com - 2012-10-15 14:24 -0700
              Re: Operation in String to Double conversion Lew <lewbloch@gmail.com> - 2012-10-15 14:48 -0700
              Re: Operation in String to Double conversion Arved Sandstrom <asandstrom2@eastlink.ca> - 2012-10-15 19:14 -0300
                Re: Operation in String to Double conversion Arne Vajhoej <arne@vajhoej.dk> - 2012-10-17 16:58 -0400
              Re: Operation in String to Double conversion Arne Vajhoej <arne@vajhoej.dk> - 2012-10-17 17:02 -0400
            Re: Operation in String to Double conversion Arne Vajhoej <arne@vajhoej.dk> - 2012-10-17 17:13 -0400
              Re: Operation in String to Double conversion Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-17 17:32 -0400
  Re: Operation in String to Double conversion Roedy Green <see_website@mindprod.com.invalid> - 2012-10-14 22:49 -0700
  Re: Operation in String to Double conversion "John B. Matthews" <nospam@nospam.invalid> - 2012-10-15 13:19 -0400
    Re: Operation in String to Double conversion Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-10-15 12:51 -0700
      Re: Operation in String to Double conversion "John B. Matthews" <nospam@nospam.invalid> - 2012-10-16 09:39 -0400
  Re: Operation in String to Double conversion Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-15 20:47 -0400
  Re: Operation in String to Double conversion Arne Vajhoej <arne@vajhoej.dk> - 2012-10-17 16:54 -0400

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