How to format a double to a certain precision?

Hi,
I have a variable of type 'double' and it's set to something like 2.3934583729. I was trying to print the double out to some standard system output with 2 decimal place, formatted precision, "2.39". It seems to me that there is no function like printf(".2f", var) in C/C++ that does the trick. Or am I overlooking something?
Any help would be greatly appreciated. Thanks.
Aaron

Yes you are over looking something.
Check this out...
import java.text.*;
public class TwoDigits
     public static final void main(String[] args) throws Exception
          double aDouble = 2.3934583729;
          DecimalFormat formatter = new DecimalFormat("#.00");
          System.out.println(" aDouble : " + formatter.format(aDouble));

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How can I format the double value?

Hi,
I am trying to format the double variable as like,
double var = 1234.56789
but i want that variable as like var = 1234.56
How can i do that in java?
Please help me.
From
Parshuram Walunjkar

Try something like the following, assume the variable 'd' underneath is your double value that you want to format.
double d = 4.45678;
NumberFormat nf = NumberFormat.getNumberInstance();
nf.setMaximumFractionDigits(5);
nf.setMinimumFractionDigits(5);
String number = nf.format(d);
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How do I get System.out.format to print out doubles with the same precision

Using the System.out.format, how do I print out the value of a double such that it looks exactly like it does if it were print from a System.out.println.
For example, take the following code:
double d = 12.48564734342343;
System.out.format("d as format: %f\n", d);
System.out.println("d as sout: " + d);Running the code, I get:

d as format: 12.485647
d as sout: 12.48564734342343

The precision of d has been lost.
I could bump up the precision as follows:
double d = 12.48564734342343;
System.out.format("d as format: %.14f\n", d);
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d as format: 12.48564734342343
d as sout: 12.48564734342343

However, that solution fails if d has a different precision, say 12.48. In that case I get:

d as format: 12.48000000000000
d as sout: 12.48

So how do I get System.out.format to print out doubles with the same precision as System.out.println?
Thanks..

YoungWinston wrote:
Schmoe wrote:
Interesting, but this is not what I am looking for...Your original question was "how do I print out the value of a double such that it looks exactly like it does if it were print from a System.out.println", and you've been told how to do that (although the pattern given by sabre may be a bit excessive - you should only need 15 '#'s).The initial phrase from my question was "Using the System.out.format, how do I..".
It's worth remembering that, unlike the Format hierarchy, 'format()' is NOT native to Java. It's a convenience implementation of the 'printf()' and 'sprintf()' methods provided in C, and first appeared in Java 1.5. Those methods were designed to produced fixed-format output; 'println()' was not.Perhaps it is the case that this can't be done.
Furthermore, Double.toString(), which is what is used by println() does not produce the same format in all cases; format("%.14f\n", d) does. TrySystem.out.println(1.8236473845783d);
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I am simply looking for a way to quickly print out multiple variables on a sysout while debugging. I want it as syntactically sweet as possible. System.out.println can be a pain when outputting multiple variables like the following:
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For some reason, my fingers always typo the plus key.
I was hoping that System.out.format would be easier,along the lines of:
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From a syntactical sweetness point of view, it is easier. However, the %f on doubles truncates the precision. I figured there must be a way to get the full precision.
DecimalFormat is syntactically sour for this purpose, as you need to instantiate the DecimalFormat.
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Part      Tag    Flag     Cylinders         Size            Blocks
0       root    wm       0 - 14086       68.35GB    (14087/0/0) 143349312
1 unassigned    wm       0                0         (0/0/0)             0
2     backup    wm       0 - 14086       68.35GB    (14087/0/0) 143349312
3 unassigned    wm       0                0         (0/0/0)             0
4 unassigned    wm       0                0         (0/0/0)             0
5 unassigned    wm       0                0         (0/0/0)             0
6 unassigned    wm       0                0         (0/0/0)             0
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0       root    wm       0 - 12865       62.43GB    (12866/0/0) 130924416
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4 unassigned    wm       0                0         (0/0/0)             0
5 unassigned    wm       0                0         (0/0/0)             0
6 unassigned    wm       0                0         (0/0/0)             0
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0       root    wm       0 - 14086       68.35GB    (14087/0/0) 143349312
1 unassigned    wu       0                0         (0/0/0)             0
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4 unassigned    wu       0                0         (0/0/0)             0
5 unassigned    wu       0                0         (0/0/0)             0
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How to format a double to a certain precision?

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