having a hard time using printf in java and reading errors in eclipse

Question

public class TryMyMath {

    public static void main(String args[])
    {

        double num = Math.E;
        printTable(num);
    }// end main

    public static void printTable(double num){
        int n = 1;

        for(n = 1;n <= 10; n++)
        {
            num = Math.pow(num, n);
            System.out.printf("%d %lf", n, num);
        }
        round100th(num);

    }
    public static double round100th(double num)
    {
        return Math.round(num*100.)/100.0 ;
    } // end round100th

}

i have this question with using printf in java, so this is the error i get with printf

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = 'l'
  at java.util.Formatter$FormatSpecifier.conversion(Unknown Source)
  at java.util.Formatter$FormatSpecifier.<init>(Unknown Source)
  at java.util.Formatter.parse(Unknown Source)
  at java.util.Formatter.format(Unknown Source)
  at java.io.PrintStream.format(Unknown Source)
  at java.io.PrintStream.printf(Unknown Source)
  at TryMyMath.printTable(TryMyMath.java:15)
  at TryMyMath.main(TryMyMath.java:7)

when i take out printf statement there wasn't any error, am I not using printf the right way it is supposed to be used in java?

and also i'm new to java and eclipse so i don't know what those error mean.

so this is the out put that i get

1 2.7182822 7.3890563 403.4287934 26489122129.8434375 13041808783936237000000000000000000000000000000000000.0000006 Infinity7 Infinity8 Infinity9 Infinity10 Infinity

the output is only right up to n = 3 i don't see anything wrong with the for loop why is this happen?

nvm i saw what wrong with it

You come from C? "%f" works for double in Java

leonbloy
– leonbloy

2012-10-04 20:05:06 +00:00
Commented Oct 4, 2012 at 20:05 — leonbloy
– leonbloy, Commented Oct 4, 2012 at 20:05

Eric · Accepted Answer · 2012-10-04 20:04:21Z

1

It should be System.out.printf("%d %f", n, num). The l is meaningless here.

Additionally, your round100th(num); call has no effect - are you trying to print the numbers to two decimal places? You can do that with:

System.out.printf("%d %.2f", n, num)

answered Oct 4, 2012 at 20:04

Eric

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Comments

Jon Lin · Accepted Answer · 2012-10-04 20:05:07Z

1

See the String Formatter Conversions, there is no %l.

answered Oct 4, 2012 at 20:05

Jon Lin

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Comments

Josiah · Accepted Answer · 2012-10-04 20:04:34Z

0

I'm not positive about this, but I believe in java you only have to use

System.out.printf(n + " " + num)

It's been awhile though, so you'll need to check it. Please tell me if I'm wrong. I don't want to leave an incorrect answer up.

answered Oct 4, 2012 at 20:04

Josiah

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Tomasz Nurkiewicz · Accepted Answer · 2012-10-04 20:05:17Z

0

Try:

System.out.printf("%d %f", n, num);

The formatting is described in great in JavaDocs.

answered Oct 4, 2012 at 20:05

Tomasz Nurkiewicz

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Comments

alfredaday · Accepted Answer · 2012-10-04 20:06:14Z

0

The problem is with this line:

System.out.printf("%d %lf", n, num);

%lf is not appropriate. Did you mean %1f? Notice that the former has a lowercase "L" and the latter has a "1". Try it with a 1 and it should work.

answered Oct 4, 2012 at 20:06

alfredaday

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2 Comments

Eric Over a year ago

"The problem is with this line:" - congratulations, you can read a stack trace - TryMyMath.java:15

Khoa Vo Over a year ago

oh i was thinking in c where you use %lf for double

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