Smalltalk › Gnu

How to get the similar effect like printf("%.7f")?

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

4 messages Options

Lee Duhem

How to get the similar effect like printf("%.7f")?

Hi,

I want to know how to get the similar effect like printf(%.7f")?

Here is how I did it:

Float extend [
printStringWithPrecision: anInteger [
<category: 'printing'>

| e value string decPointIndex endPosition tailingZeros tailingZeroNumber |

e := 1.0 / (10.0 raisedTo: anInteger).
value := self roundTo: e.

string := value printString.
decPointIndex := string findFirst: [ :c | c = $. ].

tailingZeros := ''.
endPosition := decPointIndex + anInteger.
tailingZeroNumber := endPosition - string size.
tailingZeroNumber > 0 ifTrue: [
tailingZeros := String new: tailingZeroNumber withAll: $0 ].
^(string copyFrom: 1 to: (endPosition min: string size)), tailingZeros
]
]

But I think there is a better (shorter, elegance) way to do it.

Any suggestions?

lee

_______________________________________________
help-smalltalk mailing list
[hidden email]
http://lists.gnu.org/mailman/listinfo/help-smalltalk

Paolo Bonzini-2

Re: How to get the similar effect like printf("%.7f")?

It is indeed possible to modify the basic float printing method in
Float to achieve this effect. Can you come out with a set of
printString/printOn: methods that you'd like to have, or that Squeak
and Pharo have?

Thanks,

Paolo

On Tue, Dec 15, 2009 at 15:26, Lee Duhem <[hidden email]> wrote:

> Hi,
>
> I want to know how to get the similar effect like printf(%.7f")?
>
> Here is how I did it:
>
> Float extend [
> printStringWithPrecision: anInteger [
> <category: 'printing'>
>
> | e value string decPointIndex endPosition tailingZeros tailingZeroNumber |
>
> e := 1.0 / (10.0 raisedTo: anInteger).
> value := self roundTo: e.
>
> string := value printString.
> decPointIndex := string findFirst: [ :c | c = $. ].
>
> tailingZeros := ''.
> endPosition := decPointIndex + anInteger.
> tailingZeroNumber := endPosition - string size.
> tailingZeroNumber > 0 ifTrue: [
> tailingZeros := String new: tailingZeroNumber withAll: $0 ].
> ^(string copyFrom: 1 to: (endPosition min: string size)), tailingZeros
> ]
> ]
>
> But I think there is a better (shorter, elegance) way to do it.
>
> Any suggestions?
>
> lee
>
>
> _______________________________________________
> help-smalltalk mailing list
> [hidden email]
> http://lists.gnu.org/mailman/listinfo/help-smalltalk
>
>

_______________________________________________
help-smalltalk mailing list
[hidden email]
http://lists.gnu.org/mailman/listinfo/help-smalltalk

Lee Duhem

Re: How to get the similar effect like printf("%.7f")?

On Tue, Dec 15, 2009 at 10:57 PM, Paolo Bonzini <[hidden email]> wrote:
> It is indeed possible to modify the basic float printing method in
> Float to achieve this effect. Can you come out with a set of
> printString/printOn: methods that you'd like to have, or that Squeak
> and Pharo have?
>

I'll try this.

lee

_______________________________________________
help-smalltalk mailing list
[hidden email]
http://lists.gnu.org/mailman/listinfo/help-smalltalk

Lee Duhem

Re: How to get the similar effect like printf("%.7f")?

In reply to this post by Paolo Bonzini-2

On Tue, Dec 15, 2009 at 10:57 PM, Paolo Bonzini <[hidden email]> wrote:
> It is indeed possible to modify the basic float printing method in
> Float to achieve this effect. Can you come out with a set of
> printString/printOn: methods that you'd like to have, or that Squeak
> and Pharo have?

Pharo have a method named Float>>printShowingDecimalPlaces:
do exactly what I want.

lee

_______________________________________________
help-smalltalk mailing list
[hidden email]
http://lists.gnu.org/mailman/listinfo/help-smalltalk