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Thread: numerical conversion methods..

  1. #1
    Java kindergarten chronoz13's Avatar
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    Default numerical conversion methods..

    i was looking for any methods in Math package that can convert any number such as [DECIMAL-OCTAL],
    [BINARY-OCTAL], [HEXA-OCTAL], [BINARY-HEXA], ETC.. (my proffesor told me,) but i cant find any of it,

    are there any methods such like that? or should i define my own class to perform this tasks?


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    Default Re: numerical conversion methods..

    Technically, it only matters on displaying them, or in the actual code, since when the program is running, everything is in binary. To enter a hex number add the 0x to the front of the number. Unfortunately, I don't know what to put to enter in as binary or octal, but I do know decimal has no prefix

    In the printf function, I believe if you do "%0xd", it should print out the value as a hex, but i'm not positive.

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    chronoz13 (September 24th, 2009)

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    Super Moderator Json's Avatar
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    Default Re: numerical conversion methods..

    How about this:

            System.out.println(Integer.toHexString(195012));
            System.out.println(Integer.toBinaryString(195012));
            System.out.println(Integer.toOctalString(195012));

    Expected output would be:

    2f9c4
    101111100111000100
    574704
    // Json

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    chronoz13 (September 24th, 2009)

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    Default Re: numerical conversion methods..

    Damn! thats it!!! that's what i've been looking for! tnx sir JSon!!!! your really awesome!
    i never knew that those methods were in Integer class..I thought it was in Math. Im using netbeans but i didnt notice all of those methods when everytime im using that class

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    Default Re: numerical conversion methods..

    my question is, regarding with OCTAL conversion.. why is it converted into String?
    (i understand a liitle bit with hexa and binary) ..

    and how could i reverse those methods?

    if i input
    10001110011
    and i want it to convert into a Decimal? or
    if i input
    CABACABACABA
    and i want it to convert into a Decimal?


    hmm.

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    Default Re: numerical conversion methods..

    You'll have some trouble converting the second number to an integer... it's longer than 4 bytes

    Binary String to Decimal int:

    public static int binaryToDecimal(String num)
    {
         int sum = 0;
         for (int i = 0; i <num.length(); i++)
         {
              sum += Integer.parseInt(""+num.charAt(i))*Math.pow(2,num.length()-1-i);
         }
         return sum;
    }

    Hex works basically the same way, except you have to figure out how to get the value of the number at each digit differently because parseInt doesn't recognize A-F as 10-15

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    chronoz13 (September 25th, 2009)

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    Default Re: numerical conversion methods..

    Ok, let me extend my first example.

            System.out.println("195012 hex: " + Integer.toHexString(195012));
            System.out.println("195012 binary: " + Integer.toBinaryString(195012));
            System.out.println("195012 octal: " + Integer.toOctalString(195012));
            System.out.println("From hex: " + Integer.decode("#2f9c4"));
            System.out.println("From binary: " + Integer.parseInt("101111100111000100", 2));
            System.out.println("From octal: " + Integer.decode("0574704"));

    Output:

    195012 hex: 2f9c4
    195012 binary: 101111100111000100
    195012 octal: 574704
    From hex: 195012
    From binary: 195012
    From octal: 195012
    // Json

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    chronoz13 (September 25th, 2009)

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    Default Re: numerical conversion methods..

    WOW TNX AGAIN SIR JSON!!

    TNX A LOT!!

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    Default Re: numerical conversion methods..

    ahh so thats the purpose of the .decode() method of Integer Class... tnx again!!

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    Default Re: numerical conversion methods..

    but why .parseInt in binary?

    System.out.println("From binary: " + Integer.parseInt("101111100111000100", 2));

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    Default Re: numerical conversion methods..

    Because there does not appear to be a decode for the binary number.

    // Json

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    Default Re: numerical conversion methods..

    You could also have used parseInt("12345670",8) for octal numbers.

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    Default Re: numerical conversion methods..

    Indeed

    // Json

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