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  1. #1
    pinar is offline Member
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    Default this programme dont work as I want Help me!!

    this is true output of programme /*4.3 (Conversion from kilograms to pounds) Write a program that displays the following table (note that 1 kilogram is 2.2 pounds):
    Kilograms Pounds
    1 2.2
    3 6.6

    ...
    197 433.4
    199 437.8*/

    but ı wrote
    System.out.println("kilogram" + " pound");
    for(int i=1;i<=199;i=i+2)
    {

    System.out.println(i + "" + i*2.2);

    }

    this is my output

    1 2.2
    3 6.6000000000000005
    5 11.0
    7 15.400000000000002
    9 19.8
    11 24.200000000000003
    13 28.6
    ....


    I didnt understand 6.60000000000005 instead of 6.6
    or 15.400000000002 instead of 15.4

  2. #2
    pbrockway2 is offline Moderator
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    Default

    When you display a numeric value like i*2.2 on the screen as a string you have to decide on the formatting and other properties of the string.

    At the moment you are using the println() method of System.out but there is another method you can use: printf().

    It can be a bit tricky to start with, but try

    Java Code:
    System.out.printf("%d %.2f%n", i, i*2.2);

    "%d %.2f%n" is a format string. %d means "print a decimal integer", %.2f means "print a floating point number with 2 decimal places", %n means "print a new line".

    Full details in the Formatter (Java Platform SE 6) Formatter API docs. There's a lot to digest here - but it's worth reading up on what you need on a particular occasion and going back to it as required.

    -----

    A completely different approach is to use the DecimalFormat class.

    Both approaches are covered in Oracle's Tutorial in the section Formatting Numeric Print Output.

  3. #3
    al_Marshy_1981 is offline Senior Member
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    Default

    double calculations are fairly precise, you will have to format the output
    String (Java Platform SE 6)

    I keep getting beaten to it.....
    Last edited by al_Marshy_1981; 10-27-2010 at 12:29 AM. Reason: pbrockway explained it

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