Math Not working

Discussion in 'iOS Programming' started by AGWright, Aug 27, 2012.

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  1. AGWright, Aug 27, 2012
    Last edited by a moderator: Aug 27, 2012

    AGWright macrumors newbie

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    Jun 28, 2010
    #1
    Hi

    if I use this (Hardcoding MySum)
    Code:
     NSString *mySum = @"(10+10)+25*7";
 NSNumber *result = [mySum numberByEvaluatingString];
 MyAnswerS.text = [NSString stringWithFormat:@"%@",result];
    the text box correctly displays 195 :)

    while if I build up a string to be the same @"(10+10)+25*7"
    I get the answer of 70 :(
    Code:
        NSString *mySum = [NSString stringWithFormat:@"%@",MyAnswer];
    NSNumber *result = [mySum numberByEvaluatingString];
    MyAnswerS.text = [NSString stringWithFormat:@"%@",result];
    debugging MyAnswer shows @"(10+10)+25*7"

    any Ideas

    Best Regards
     
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  2. jnoxx, Aug 27, 2012

    jnoxx macrumors 65816

    jnoxx

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    #2
    Why do you use strings instead of NSNumbers/Ints/Floats?
     
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  3. balamw, Aug 27, 2012

    balamw Moderator

    balamw

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    #3
    A bit of context would definitely be helpful, but I suspect the OP is trying to make an app where the user can enter an arbitrary formula and have it evaluated.

    B
     
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  4. AGWright, Aug 27, 2012

    AGWright thread starter macrumors newbie

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    #4
    Yep sorry the user get a series of numbers and have to make it add up to a target
    I.e target = 195
    Sum = (10+10) + 25 * 7
     
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  5. balamw, Aug 27, 2012

    balamw Moderator

    balamw

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    #5
    Break the problem down. Does it work consistently for a simpler expression, e.g. 2+2?

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  6. AGWright, Aug 27, 2012

    AGWright thread starter macrumors newbie

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    #6
    yep works if I do 2+2 and 9*9 but if I do 10*9 I get 0 so tried 12*9 and I got 18
    so its not 'seeing' the 1 as in 12 but just sees 2*9
     
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  7. balamw, Aug 27, 2012

    balamw Moderator

    balamw

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    #7
    What does it do for 9*10? How about (10*9)?

    B
     
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  8. dejo, Aug 27, 2012

    dejo Moderator

    dejo

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    #8
    What are MyAnswer and MyAnswerS?
     
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  9. chown33, Aug 27, 2012

    chown33 macrumors 604

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    #9
    Break it down more. Run more tests, like 9*12 or 32*9 or 200*9, or put a space before 12*9.

    And when you do these tests, post the code for them, as well as the results. Your first post failed to show the code that builds the string. Seeing the string-builder code might be a valuable clue. In addition, someone else could actually compile and test the code themselves, rather than you being the only one who can do it.

    Also please tell us where you got the code that adds the numberByEvaluatingString capability. AFAICT it's not a standard NSString method. Sometimes people get older versions of third-party libraries, and see bugs that have been fixed in newer versions.
     
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  10. AGWright, Aug 27, 2012

    AGWright thread starter macrumors newbie

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    #10
    found out that replacing any spaces worked (why it was putting spaces in who knows)

    stringByReplacingOccurrencesOfString:mad:" " withString:mad:""];

    now working :) thank to all who answered :)
     
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  11. balamw, Aug 27, 2012

    balamw Moderator

    balamw

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    #11
    So were there embedded spaces in that? Where? Can you copy and paste the actual faulty input.

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  12. Duncan C, Aug 27, 2012

    Duncan C macrumors 6502a

    Duncan C

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    #12

    Where does teh numberByEvaluatingString method come from? I don't see it in any of Apple's frameworks. Searching the net, I found something called DDMathParser. Is that it?

    For future reference, its a REALLY good idea to list any third party libraries that you are using, along with a link to info on those libraries. Otherwise, we have no idea what you are using.

    You should also provide a brief summary of those libraries, what functions they provide, and how you think they are supposed to work.

    e.g.:

     
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  13. AGWright, Aug 27, 2012

    AGWright thread starter macrumors newbie

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    #13
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