String formatting doubt

[Nik Arora]

Hi All,
Can anybody explain me the below program?

source: k&b

int i1=-123;
int i2=12345;
System.out.printf(">%1$(7d< \n", i1);
System.out.printf(">%0, 7d< \n", i2);
System.out.printf(">%+-7d< \n", i2);
System.out.printf(">%2$b + %1$5d< \n", i1,false);


output is:

> (123) <
>012,345<
>+12345 <
>false + -123<

Please explain me how it works



Thanks All

[John Stone]

take a look at:
http://java.sun.com/javase/6/docs/api/java/util/Formatter.html#syntax

an in case you already did, what part troubles you?
[ May 07, 2007: Message edited by: John Stone ]

[Nik Arora]

Hi John,
My doubts are

1. Why the output is positive that is (123) in the first case

2. Why the output is 012,345 in the second case and i didnt understand the 3rd and the 4th output also.

[Chandra Bhatt]

int i1=-123;
int i2=12345;
System.out.printf(">%1$(7d< \n", i1);
System.out.printf(">%0, 7d< \n", i2);

flags
1- "(" means enclose negative numbers inside the parenthesis
2- "0" says, there should be padding to this argument with zeroes

[Nik Arora]

Hi chandra,
In case of second output after 012 why "," has come.When the below line is executed output is +12345 i am not understanding can you explain me

System.out.printf(">%+-7d< \n", i2);

[Chandra Bhatt]

Originally posted by nik arora:
Hi chandra,
In case of second output after 012 why "," has come.When the below line is executed output is +12345 i am not understanding can you explain me

System.out.printf(">%+-7d< \n", i2);

From K&B Page 490:

"," Use local-specific grouping separators (i.e. the comma in 123,456)

[swarna dasa]

"," was used to format the decimal.

Use :
System.out.printf(">%07d< \n", i2);

To get:
0012345

[Nik Arora]

Hi Chandra,
Look at the below statement
i2=12345;
System.out.printf(">%0, 7d< \n", i2);

The output produced for this is 012,345 why after 012 the "," has come.

[Chandra Bhatt]

Originally posted by nik arora:
Hi Chandra,
Look at the below statement
i2=12345;
System.out.printf(">%0, 7d< \n", i2);

The output produced for this is 012,345 why after 012 the "," has come.

Grouping of digits
each comma after three digits from right.

1,234
12,345
123,456
1,234,567
12,345,678
123,456,789

And this is the way I get it, I don't remember why is so; but there is
some simple logic behind this for sure.

Thanks,
[ May 07, 2007: Message edited by: Chandra Bhatt ]

[megha joshi]

The output produced for this is 012,345 why after 012 the "," has come.

I get the output as 12,345 instead of the 0 in front for the line System.out.printf(">%0, 7d< \n", i2);

I think its the Eclipse IDE or my installed compiler that is causing this issue. Just wanted to confirm that 0 should be included as per rules.

Thanks,
Megha

[Chandra Bhatt]

Hi Megha,

do this,

System.out.printf(">%0,7d< \n", i2);

You left one space between , and 7 so space included in padding.


Thanks,

[megha joshi]

Hi Chandra,
Thanks for the prompt response.

I think it was a typo in original question.

Thanks for clarification.I think Space is a new rule. One space is allowed and included before 0s used for padding. More than one space gives formatexception. But it wont be on exam

Thanks,
Megha

[Nik Arora]

HI Megha,
Why the "," is coming after 012?

[Chandra Bhatt]

Hi Nikhil,


There is no role of leading stuffed zeros in grouping of digits.



Thanks,

[Nik Arora]

I am not getting at all chandra

[John Stone]

Originally posted by nik arora:
HI Megha,
Why the "," is coming after 012?

as Chandra wrote:
[code]
Grouping of digits
[/code[

In some contries, there is a custom, that large numbers are written by using "separators" between digits, usually grouped by 3. This is mainly to improve - to easy reading of such big numbers for humans.

If I write
1000000000000
Can you tell how many zeroes are there? Yes of course, but you spend a while counting them.

If I write
1 000 000 000
you can immeadiatly tell, that there are 9 zeroes, you know that there are 3 digits in each group,.. so you just count groups.

In some countries, these separators may be different.
1,000,000,000 -> here "," is separating groups of digits.

If you are using Windows, go to Control Panel -> Regional and Language Options. And by the field of your settings, click customize and see "Digit grouping symbol".

I guess, that the whole point of "," used in Formatter class is that, it is separating groups of digits according to settings for your country (or the settings you are using, if those are different)

[Nik Arora]

HI JOHN,

When the below statement is executed the output is
>+12345<. Can you explain me how?

i2=12345;
System.out.printf(">%+-7d< \n", i2);

[Chandra Bhatt]

Originally posted by nik arora:
HI JOHN,

When the below statement is executed the output is
>+12345<. Can you explain me how?

i2=12345;
System.out.printf(">%+-7d< \n", i2);

That "-" is flag, that says to left justify the argument.

See the difference in output with/without using that flag "-"

int i2=12345;
System.out.printf(">%+7d< \n", i2);

Output:
> +12345<

int i2=12345;
System.out.printf(">%+-7d< \n", i2);

Output:
>+12345 <



Thanks,

[Nik Arora]

Thanks chandra got