Having Trouble with boolean

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  1. #1
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    Having Trouble with boolean

    Hey guys

    i've just started learning C++ and im stuck with boolean

    in the tutorial it shows:


    Code:
    A. !( 1 || 0 )         ANSWER: 0	
    B. !( 1 || 1 && 0 )    ANSWER: 0 (AND is evaluated before OR)
    C. !( ( 1 || 0 ) && 0 )  ANSWER: 1 (Parenthesis are useful)
    When i put one of these in Dev-C++ tells me: expected unqualified-id before '!' token

    if someone could tell me what i am doing wrong it would be great.

    Thanks

    P.S sorry huys, i accidently posted this twice
    My apologies
    Last edited by jazza_rockz; 05-13-2008 at 04:37 AM. Reason: had to apologise for posting twice

  2. #2
    C++ Witch laserlight's Avatar
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    What did you try? This works for me:
    Code:
    #include <iostream>
    
    int main()
    {
        std::cout << !( 1 || 0 ) << std::endl;
    }
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    Now that i look at it, i havent actually gotten as far as std::cout << !( 1 || 0 ) << std::endl;
    so i don't exactly know what it is im doing.

    is there any other way to do it?
    Last edited by jazza_rockz; 05-13-2008 at 04:41 AM.

  4. #4
    C++まいる!Cをこわせ!
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    Sure,
    bool b = !( 1 || 0 );

    You must assign the expression somewhere, though.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  5. #5
    C++ Witch laserlight's Avatar
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    is there any other way to do it?
    Eh, your idea is to evaluate the expression and print out the result to see for yourself, right? Then it is as simple as that. What else did you have in mind?
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    Post your code that isn't working...

  7. #7
    Registered User delgelato's Avatar
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    Emm I just started learning C++, and programming in general, but anyways hello nice to meet you all.

    Anyways, I happen to get the same problem as the TS, I think what he's trying to say is how to apply the boolean operator in an IF statement.

    Well, at least thats where my problem is.

    I tried:

    Code:
    if(age > 20 &#37;% age < 25)
    To make if the input is more than 20 and less than 25 but its still doesn't work.

    edit:
    LOL sorry to bother you it's supposed to be &&, the font makes it hard to see the difference >_< and I never look at what I press so...Anyways I found the problem >_>

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