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Reach a digit of numerical value in array index.

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  Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-17 14:15 -0700
    Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-17 14:34 -0700
      Re: Reach a digit of numerical value in array index. JJ <jj4public@vfemail.net> - 2015-03-18 13:38 +0700
        Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-18 06:57 -0700
    Re: Reach a digit of numerical value in array index. Norman Peelman <npeelman@cfl.rr.com> - 2015-03-18 23:49 -0400
      Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-19 01:16 -0700
        Re: Reach a digit of numerical value in array index. John Harris <niam@jghnorth.org.uk.invalid> - 2015-03-19 09:28 +0000
          Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-19 05:00 -0700
            Re: Reach a digit of numerical value in array index. John Harris <niam@jghnorth.org.uk.invalid> - 2015-03-19 16:23 +0000
              Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-19 10:43 -0700
                Re: Reach a digit of numerical value in array index. "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-03-19 19:51 +0100
                Re: Reach a digit of numerical value in array index. John Harris <niam@jghnorth.org.uk.invalid> - 2015-03-22 11:20 +0000
                  Re: Reach a digit of numerical value in array index. jonas.thornvall@gmail.com - 2015-03-22 08:18 -0700
          Re: Reach a digit of numerical value in array index. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-03-19 15:59 +0100
            Re: Reach a digit of numerical value in array index. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-03-19 16:13 +0100
            Re: Reach a digit of numerical value in array index. Dr J R Stockton <reply1500@merlyn.demon.co.uk.invalid> - 2015-03-20 23:50 +0000
              Re: Reach a digit of numerical value in array index. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-03-22 16:29 +0100
                Re: Reach a digit of numerical value in array index. Scott Sauyet <scott@sauyet.com> - 2015-03-22 17:36 -0400
                Re: Reach a digit of numerical value in array index. Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-03-22 21:26 -0300
                  Re: Reach a digit of numerical value in array index. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-03-23 05:54 +0100

#27063 — Reach a digit of numerical value in array index.

var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.

i=0;
result[i]=compute[0][i]+compute[1][i]; //Well this does not work

Is it even possible without saving the index?
Is this really necessary?
i=0;
intA=compute[0];
intB=compute[1]
result[i]=intA+intB;

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#27064

Den tisdag 17 mars 2015 kl. 22:16:04 UTC+1 skrev jonas.t...@gmail.com:
> var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.
> 
> i=0;
> result[i]=compute[0][i]+compute[1][i]; //Well this does not work
> 
> Is it even possible without saving the index?
> Is this really necessary?
> i=0;
> intA=compute[0];
> intB=compute[1]
> result[i]=intA+intB;

Ok i am tired, there is no way to reach the index witin an integer in javascript?
It seem it was very stupid of me converting the strings to numbers in the first place.

But really?

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#27065

On Tue, 17 Mar 2015 14:34:56 -0700 (PDT), jonas.thornvall@gmail.com wrote:
> Den tisdag 17 mars 2015 kl. 22:16:04 UTC+1 skrev jonas.t...@gmail.com:
>> var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.
>> 
>> i=0;
>> result[i]=compute[0][i]+compute[1][i]; //Well this does not work

From what I can see, it doesn't work because "result" is not yet defined.

>> Is it even possible without saving the index?
>> Is this really necessary?
>> i=0;
>> intA=compute[0];
>> intB=compute[1]
>> result[i]=intA+intB;

Yes: result[0]=intA+intB;

> Ok i am tired, there is no way to reach the index witin an integer in javascript?

If you meant to get the index of a specific value of an array, use this:

var valueToSearch = 3;
var valueIndex = myArray.indexOf(valueToSearch);

> It seem it was very stupid of me converting the strings to numbers in the first place.
> 
> But really?

What string?

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#27066

Den onsdag 18 mars 2015 kl. 07:38:29 UTC+1 skrev JJ:
> On Tue, 17 Mar 2015 14:34:56 -0700 (PDT), jonas.thornvall@gmail.com wrote:
> > Den tisdag 17 mars 2015 kl. 22:16:04 UTC+1 skrev jonas.t...@gmail.com:
> >> var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.
> >> 
> >> i=0;
> >> result[i]=compute[0][i]+compute[1][i]; //Well this does not work
> 
> From what I can see, it doesn't work because "result" is not yet defined.

No it really does not work, compute is an array of integers, and you can not treat it as a two dimensional array to reach a digit.


> >> Is it even possible without saving the index?
> >> Is this really necessary?
> >> i=0;
> >> intA=compute[0];
> >> intB=compute[1]
> >> result[i]=intA+intB;
> 
> Yes: result[0]=intA+intB;
> 
> > Ok i am tired, there is no way to reach the index witin an integer in javascript?
> 
> If you meant to get the index of a specific value of an array, use this:
> 
> var valueToSearch = 3;
> var valueIndex = myArray.indexOf(valueToSearch);

I think that the result not an integer from indexOf, and than it does not make sense to use parseInt again.

> > It seem it was very stupid of me converting the strings to numbers in the first place.
> > 
> > But really?
> 
> What string?

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#27070

On 03/17/2015 05:15 PM, jonas.thornvall@gmail.com wrote:
> var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.
>
> i=0;
> result[i]=compute[0][i]+compute[1][i]; //Well this does not work
>
> Is it even possible without saving the index?
> Is this really necessary?
> i=0;
> intA=compute[0];
> intB=compute[1]
> result[i]=intA+intB;
>

  You aren't dealing with strings here, it doesn't work that way.


-- 
Norman
Registered Linux user #461062
AMD64X2 6400+ Ubuntu 10.04 64bit

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#27071

Den torsdag 19 mars 2015 kl. 04:49:49 UTC+1 skrev Norman Peelman:
> On 03/17/2015 05:15 PM, jonas.thornvall@gmail.com wrote:
> > var Compute=[] is an array/stack holding integer values now i want to add individual digits store them in result.
> >
> > i=0;
> > result[i]=compute[0][i]+compute[1][i]; //Well this does not work
> >
> > Is it even possible without saving the index?
> > Is this really necessary?
> > i=0;
> > intA=compute[0];
> > intB=compute[1]
> > result[i]=intA+intB;
> >
> 
>   You aren't dealing with strings here, it doesn't work that way.
> 
> 
> -- 
> Norman
> Registered Linux user #461062
> AMD64X2 6400+ Ubuntu 10.04 64bit

Well i know howto do it, but its insane, i questioning why one can not read/reach the digit place of a number stored in an array, without going via temp variables. There should be a way reading them straight out of the index. 

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#27073

On Thu, 19 Mar 2015 01:16:40 -0700 (PDT), jonas.thornvall@gmail.com
wrote:


  <snip>
>Well i know howto do it, but its insane, 
>i questioning why one can not read/reach the digit place 
>of a number stored in an array, without going via temp variables. 
>There should be a way reading them straight out of the index. 

Why should there be?

Remember that what's stored are binary numbers. Do you really want to
fetch a binary digit?

  John

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#27075

Den torsdag 19 mars 2015 kl. 10:28:12 UTC+1 skrev John Harris:
> On Thu, 19 Mar 2015 01:16:40 -0700 (PDT), jonas.thornvall@gmail.com
> wrote:
> 
> 
>   <snip>
> >Well i know howto do it, but its insane, 
> >i questioning why one can not read/reach the digit place 
> >of a number stored in an array, without going via temp variables. 
> >There should be a way reading them straight out of the index. 
> 
> Why should there be?
> 
> Remember that what's stored are binary numbers. Do you really want to
> fetch a binary digit?
> 
>   John

Yeah why not i guess that make the adder faster, doing bit addition rather than byte. Well it may end up being the same work but that is not the point.

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#27079

On Thu, 19 Mar 2015 05:00:36 -0700 (PDT), jonas.thornvall@gmail.com
wrote:

>Den torsdag 19 mars 2015 kl. 10:28:12 UTC+1 skrev John Harris:
>> On Thu, 19 Mar 2015 01:16:40 -0700 (PDT), jonas.thornvall@gmail.com
>> wrote:
>> 
>> 
>>   <snip>
>> >Well i know howto do it, but its insane, 
>> >i questioning why one can not read/reach the digit place 
>> >of a number stored in an array, without going via temp variables. 
>> >There should be a way reading them straight out of the index. 
>> 
>> Why should there be?
>> 
>> Remember that what's stored are binary numbers. Do you really want to
>> fetch a binary digit?
>> 
>>   John
>
>Yeah why not i guess that make the adder faster, doing bit addition rather than byte. Well it may end up being the same work but that is not the point.

On second thoughts I haven't the faintest idea what you are saying and
what your question is.

Are you talking about an array of ECMAScript numbers, an array of
strings holding a representation of a big number, or an array of
arrays of ECMAScript numbers holding a representation of a big number?


  John

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#27081

Den torsdag 19 mars 2015 kl. 17:23:18 UTC+1 skrev John Harris:
> On Thu, 19 Mar 2015 05:00:36 -0700 (PDT), jonas.thornvall@gmail.com
> wrote:
> 
> >Den torsdag 19 mars 2015 kl. 10:28:12 UTC+1 skrev John Harris:
> >> On Thu, 19 Mar 2015 01:16:40 -0700 (PDT), jonas.thornvall@gmail.com
> >> wrote:
> >> 
> >> 
> >>   <snip>
> >> >Well i know howto do it, but its insane, 
> >> >i questioning why one can not read/reach the digit place 
> >> >of a number stored in an array, without going via temp variables. 
> >> >There should be a way reading them straight out of the index. 
> >> 
> >> Why should there be?
> >> 
> >> Remember that what's stored are binary numbers. Do you really want to
> >> fetch a binary digit?
> >> 
> >>   John
> >
> >Yeah why not i guess that make the adder faster, doing bit addition rather than byte. Well it may end up being the same work but that is not the point.
> 
> On second thoughts I haven't the faintest idea what you are saying and
> what your question is.
> 
> Are you talking about an array of ECMAScript numbers, an array of
> strings holding a representation of a big number, or an array of
> arrays of ECMAScript numbers holding a representation of a big number?
> 
> 
>   John

It did hold integers, but i changed the code so it is a none issue now, i just remarked on that there is no simple way to read out a digit of an integer stored at an index within an array.

That is all.

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#27082

jonas.thornvall@gmail.com wrote on 19 mrt 2015 in comp.lang.javascript:

> It did hold integers, but i changed the code so it is a none issue now,

This is usenet, 
you don't decide whether something becomes a "non-issue",
when you change something.

btw, what is a "none issue"?
Or is that a non-issue too?

> i just remarked on that there is no simple way to read out a digit of an
> integer stored at an index within an array. 

Nonsense.

It is impossible to determine, because,
independent of where the integer is stored,
it is stored as a floating point binary variable,
so "digit" has no fixed meaning here.

-- 
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

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#27099

On Thu, 19 Mar 2015 10:43:58 -0700 (PDT), jonas.thornvall@gmail.com
wrote:

>Den torsdag 19 mars 2015 kl. 17:23:18 UTC+1 skrev John Harris:

  <snip> 
>> On second thoughts I haven't the faintest idea what you are saying and
>> what your question is.
>> 
>> Are you talking about an array of ECMAScript numbers, an array of
>> strings holding a representation of a big number, or an array of
>> arrays of ECMAScript numbers holding a representation of a big number?
  <snip> 

>i just remarked on that there is no simple way to read out a digit of an 
>integer stored at an index within an array.

So you call this function and it returns 7 if it's currently a decimal
integer, E if a hexadecimal integer, 2 if a ternary integer, 0 if it's
a binary integer.

How can you say it's a 'simple way' ?

  John

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#27100

Den söndag 22 mars 2015 kl. 12:20:52 UTC+1 skrev John Harris:
> On Thu, 19 Mar 2015 10:43:58 -0700 (PDT), jonas.thornvall@gmail.com
> wrote:
> 
> >Den torsdag 19 mars 2015 kl. 17:23:18 UTC+1 skrev John Harris:
> 
>   <snip> 
> >> On second thoughts I haven't the faintest idea what you are saying and
> >> what your question is.
> >> 
> >> Are you talking about an array of ECMAScript numbers, an array of
> >> strings holding a representation of a big number, or an array of
> >> arrays of ECMAScript numbers holding a representation of a big number?
>   <snip> 
> 
> >i just remarked on that there is no simple way to read out a digit of an 
> >integer stored at an index within an array.
> 
> So you call this function and it returns 7 if it's currently a decimal
> integer, E if a hexadecimal integer, 2 if a ternary integer, 0 if it's
> a binary integer.
> 
> How can you say it's a 'simple way' ?
> 
>   John

Well you know as well as i that ECMA script is full of functions doing type transformations.

I just noticed there is none that work on index in an array.

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#27076

John Harris wrote:

> […] jonas.thornvall@gmail.com wrote:
>> Well i know howto do it, but its insane,
>> i questioning why one can not read/reach the digit place
>> of a number stored in an array, without going via temp variables.
>> There should be a way reading them straight out of the index.

> Why should there be?
> 
> Remember that what's stored are binary numbers. Do you really want to
> fetch a binary digit?

ACK.  That said, there are (at least) three ways to retrieve the decimal 
digit from a Number value without a "temporary variable"; just error-prone 
and not very efficient ones (so kids, don’t do this at home):

a) n.toString().charAt(i)
b) n.toString().slice(-j, -j + 1)
c) (n % Math.pow(10, j)).toString().charAt(0)

where “n” is (a variable storing) the Number value (preferably a numeric 
integer), “i” is (a variable storing) the 0-based index of the digit counted 
from the left, and “j” is (a variable storing) the 1-based index of the 
digit counted from the right.

I do not think I need to explain why these approaches are not very 
efficient.  They are also error-prone because of limited precision of the 
IEEE 754 double-precision floating-point format as such, and of the string 
representation of its values in ECMAScript.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#27077

Thomas 'PointedEars' Lahn wrote:

> […] there are (at least) three ways to retrieve the decimal
> digit from a Number value without a "temporary variable"; just error-prone
> and not very efficient ones (so kids, don’t do this at home):
> 
> a) n.toString().charAt(i)
> b) n.toString().slice(-j, -j + 1)
> c) (n % Math.pow(10, j)).toString().charAt(0)
> 
> where “n” is (a variable storing) the Number value (preferably a numeric
> integer), “i” is (a variable storing) the 0-based index of the digit
> counted from the left, and “j” is (a variable storing) the 1-based index
> of the digit counted from the right.
> 
> I do not think I need to explain why these approaches are not very
> efficient.  They are also error-prone because of limited precision of the
> IEEE 754 double-precision floating-point format as such, and of the string
> representation of its values in ECMAScript.

For recreation, here is another one:

d) Math.floor((n % Math.pow(10, j)) / Math.pow(10, j - 1))

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#27093

In comp.lang.javascript message <2641901.31sAzN5gEV@PointedEars.de>,
Thu, 19 Mar 2015 15:59:25, Thomas 'PointedEars' Lahn
<PointedEars@web.de> posted:

>ACK.  That said, there are (at least) three ways to retrieve the decimal
>digit from a Number value without a "temporary variable"; just error-prone
>and not very efficient ones (so kids, don’t do this at home):
>
>a) n.toString().charAt(i)
>b) n.toString().slice(-j, -j + 1)
>c) (n % Math.pow(10, j)).toString().charAt(0)
>
>where “n” is (a variable storing) the Number value (preferably a numeric
>integer), “i” is (a variable storing) the 0-based index of the digit counted
>from the left, and “j” is (a variable storing) the 1-based index of the
>digit counted from the right.
>
>I do not think I need to explain why these approaches are not very
>efficient.  They are also error-prone because of limited precision of the
>IEEE 754 double-precision floating-point format as such, and of the string
>representation of its values in ECMAScript.

Efficiency may not be important, but correctness usually is.
Consider and test


        j = 3
        n = 12345 ; X = (n % Math.pow(10, j)).toString().charAt(0)
        n = 12045 ; Y = (n % Math.pow(10, j)).toString().charAt(0)
        n = 00345 ; Z = (n % Math.pow(10, j)).toString().charAt(0)
        Z = [X, Y, Z]        ///// ->    3, 4, 2

in which Z is present for amazement/amusement only.

**TESTED** in current Firefox.

-- 
 (c) John Stockton, nr London, UK.  For Mail, see Home Page.  Turnpike, WinXP.
 Web  <http://www.merlyn.demon.co.uk/> - FAQ-type topics, acronyms, and links.
 Command-prompt MiniTrue is useful for viewing/searching/altering files. Free,
 DOS/Win/UNIX now 2.0.6;  see my <http://www.merlyn.demon.co.uk/pc-links.htm>.

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#27101

Dr J R Stockton wrote:

> [A long time ago, in a galaxy far, far away] Thomas 'PointedEars' Lahn 
> [posted this story: ]

When will you stop posting those attribution novels?

> Consider and test
> 
> 
>         j = 3
>         n = 12345 ; X = (n % Math.pow(10, j)).toString().charAt(0)
>         n = 12045 ; Y = (n % Math.pow(10, j)).toString().charAt(0)
>         n = 00345 ; Z = (n % Math.pow(10, j)).toString().charAt(0)
>         Z = [X, Y, Z]        ///// ->    3, 4, 2

Right, you would need to pad the toString() result if the result of the “%” 
operation would be smaller than the 1-based index (j).  I *did* test this 
approach before posting it – even though I also *did* point out *twice* that 
it is error-prone –, but not with such numbers.

> in which Z is present for amazement/amusement only.

Numeric integer literals with leading zero are parsed as octal in Mozilla 
JavaScript (and not a syntax error) when not in strict mode.  No surprise 
here.

> **TESTED** in current Firefox.

Confirmed in Iceweasel 31.5.0 (“current” is not a sensible designation, 
especially not with rapid releases).

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#27104

Thomas 'PointedEars' Lahn wrote: 

> Dr J R Stockton wrote:
> 
> > [A long time ago, in a galaxy far, far away] Thomas 'PointedEars' Lahn 
> > [posted this story: ]
> 
> When will you stop posting those attribution novels?

Dr. Stockton has long made it clear that he doesn't agree with you on 
this issue.  Is there a reason to continue to pursue it?

Moreover, his attribution took 148 characters and three newlines.  Your 
rebuke took 147 characters and four newlines.  How does that help?

And now I'm adding to it!  :-(

  -- Scott

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#27105

Thomas 'PointedEars' Lahn wrote:
> Dr J R Stockton wrote:
>

>> Consider and test
>>
>>
>>          j = 3
>>          n = 12345 ; X = (n % Math.pow(10, j)).toString().charAt(0)
>>          n = 12045 ; Y = (n % Math.pow(10, j)).toString().charAt(0)
>>          n = 00345 ; Z = (n % Math.pow(10, j)).toString().charAt(0)
>>          Z = [X, Y, Z]        ///// ->    3, 4, 2
>
> Right, you would need to pad the toString() result if the result of the “%”
> operation would be smaller than the 1-based index (j).  I *did* test this
> approach before posting it – even though I also *did* point out *twice* that
> it is error-prone –, but not with such numbers.
>

<snip>

>
> Numeric integer literals with leading zero are parsed as octal in Mozilla
> JavaScript (and not a syntax error) when not in strict mode.  No surprise
> here.
>
>> **TESTED** in current Firefox.
>
> Confirmed in Iceweasel 31.5.0 <snip>
>

Confirmed in Chrome 41 and IE 11 as well.

   0345 // 229 [Z]
   03458 // 3458
   077 // 63
   078 // 78
   01234567 // 342391
   012345678 // 12345678
   0123456789 // 123456789

[1] <http://ecma-international.org/ecma-262/5.1/#sec-7.8.3>
     <http://ecma-international.org/ecma-262/5.1/#sec-B.1.1>

A conforming implementation, when processing strict mode code (#10.1.1), 
must not extend the syntax of NumericLiteral to include 
OctalIntegerLiteral as described in B.1.1.

In ECMAScript 6, octal number syntax uses a leading zero followed by a 
lowercase or uppercase Latin letter "O" (0o or 0O).


-- 
Joao Rodrigues

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#27106

Joao Rodrigues wrote:

> [1] <http://ecma-international.org/ecma-262/5.1/#sec-7.8.3>
>      <http://ecma-international.org/ecma-262/5.1/#sec-B.1.1>
> 
> A conforming implementation, when processing strict mode code (#10.1.1),
> must not extend the syntax of NumericLiteral to include
> OctalIntegerLiteral as described in B.1.1.
> 
> In ECMAScript 6, octal number syntax uses a leading zero followed by a
> lowercase or uppercase Latin letter "O" (0o or 0O).

ACK, thx.

You should use quotation marks or the “|” prefix to make clear which 
statements are quotations from references and which are your own.

Also, ECMAScript Edition 6 is still a working draft.  References to it 
should reflect that fact.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.

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