Expression Manipulator v0.1

This is a discussion on Expression Manipulator v0.1 within the A Brief History of Cprogramming.com forums, part of the Community Boards category; Yes, I know those circumventions are possible, but the computer should adapt to the user, not vice verca. The user ...

  1. #16
    S Sang-drax's Avatar
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    Yes, I know those circumventions are possible, but the computer should adapt to the user, not vice verca.
    The user should not have to remember to add an extra space after a minus sign.
    Last edited by Sang-drax : Tomorrow at 02:21 AM. Reason: Time travelling

  2. #17
    Just because ygfperson's Avatar
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    (a+b)(c+d) does work fine. In some situations the parentheses surrounding the expression don't show when they should, so I'll have to tweak that.

    x(a+b) isn't allowed because x() is handled like a function. Graphing calculators have the same problem. The only way I can see to allow that is to differentiate between functions and variables at run-time, which means pre-defining the names of each before using them.

    I might be able to tweak minus signs to work correctly in situations. Graphing calculators solve this problem by having a different minus sign than their negative sign. Anyone have any ideas for rules regarding the dash? (ie: if letter before and afterwards, it's a minus sign)

  3. #18
    C++ Developer XSquared's Avatar
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    Wouldn't it always be possible to interpret it as a negative sign?

    4-n = 4+(-n)
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

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  4. #19
    Just because ygfperson's Avatar
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    Originally posted by XSquared
    Wouldn't it always be possible to interpret it as a negative sign?

    4-n = 4+(-n)
    But that could also be
    4-n = 4(-n)

  5. #20
    Pursuing knowledge confuted's Avatar
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    Most people would probably write that as 4*-n though, or use 4(-n). I don't think anyone would type 4-n and intend 4 times negative n.

    edit: impressive program anyway
    Last edited by confuted; 05-18-2003 at 03:14 PM.
    Away.

  6. #21
    Just because ygfperson's Avatar
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    so... ignoring whitespace, it's a minus sign unless
    1) It's preceded by a plus sign
    2) it's preceded by a parenthesis
    3) it's the first character in the string
    4) it's preceded by a '*'

    This sound good?

    thanks for your input, btw

  7. #22
    Pursuing knowledge confuted's Avatar
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    That sounds excellent
    Away.

  8. #23
    C++ Developer XSquared's Avatar
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    So you can't divide by a negative number, according to your rules...
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  9. #24
    Just because ygfperson's Avatar
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    Originally posted by XSquared
    So you can't divide by a negative number, according to your rules...
    5) It's preceded by a '/'

    BTW, the '/' serves to raise the next factor in the string by -1 power. Negative signs are skipped past, because there's never any intention to divide just by a negative 1.

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