negative to posative

This is a discussion on negative to posative within the C++ Programming forums, part of the General Programming Boards category; How can i make -a into +a?...

  1. #1
    Mmm. Purple.
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    negative to posative

    How can i make -a into +a?

  2. #2
    lurker
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    Multiply by -1.

  3. #3
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    Or you can use the absolute value function.
    http://www.cprogramming.com/fod/abs.html
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  4. #4
    moi
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    Originally posted by gamer4life687
    Or you can use the absolute value function.
    http://www.cprogramming.com/fod/abs.html
    that page is 100% wrong. there is no abs() which takes and returns an int!
    hello, internet!

  5. #5
    Cheesy Poofs! PJYelton's Avatar
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    If you want to change the sign on any variable just do:
    Code:
    a=-a;
    But if you only want to change negatives to positives, not the other way around, then use the absolute value function.

  6. #6
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    Code:
    Originally posted by Moi
    that page is 100% wrong. there is no abs() which takes and returns an int

    Its funny you say it doesnt work. I tested the exact program on that site and it works 100%!. Maybe your compiler doesnt have that.
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  7. #7
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    Originally posted by gamer4life687
    Its funny you say it doesnt work. I tested the exact program on that site and it works 100%!. Maybe your compiler doesnt have that. [/B]
    Right, you should mention your compiler on for example
    mathematical questions

  8. #8
    moi
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    think before you speak

    of course the program will work, ints and doubles can be implicitly converted around. that is not what i said though.
    hello, internet!

  9. #9
    ATH0 quzah's Avatar
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    Simply return 0 - x.

    Quzah.
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  10. #10
    UNBANNED OneStiffRod's Avatar
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    To get the inverse of a number...

    Code:
    //To get the (-) negative equiv. of 100 (-100) just reverse the bits and add 1, 
    //same for negative to positive.
    
    int main(){
    	int i = 100;
            i = ~i + 1;
    	cout<<i<<endl;
    	return 0;
    }
    OR Multiply by -1.
    Last edited by OneStiffRod; 12-27-2002 at 08:15 PM.
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  11. #11
    moi
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    ahh, i see. there is an int abs (int), but its in <stdlib.h>, not <math.h>. therefore the flaw in the tutorial program is #including the wrong header file, because without <stdlib.h> int abs (int) is not in scope, and double abs (double) is used with implicit conversions (although if <stdlib.h> had been there it would use an overloaded abs() instead). happy now?
    hello, internet!

  12. #12
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    Interesting what we can come up with with only one arguement. I sure hope that KrappyKoder responds to this and gets his answer. Now that we know how to do the change plz lets not argue anymore. I get the point.
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  13. #13
    I lurk
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    No, clearly the best solution is the following:

    Code:
    int a = -4394;
    
    for (int i = 0; i < a*-2; i++)
    a++;

  14. #14
    Mmm. Purple.
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    meh

    The method i ended up using was from a friend, playing with unsigned and signed

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