Padding fixed-length strings

[Richard Maher]

Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

Cheers Richard Maher

[Randy Webb]

Richard Maher said the following on 4/13/2007 10:35 PM:

Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

--
Randy
Chance Favors The Prepared Mind
comp.lang.javascript FAQ - http://jibbering.com/faq/index.html
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[-Lost]

"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...

Richard Maher said the following on 4/13/2007 10:35 PM:

>Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

Well, um, to quote you, "Did you test that?" : )

-Lost

[Lee]

-Lost said:

>
"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...

>Richard Maher said the following on 4/13/2007 10:35 PM:

>>Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

Well, um, to quote you, "Did you test that?" : )

Did you? What seems to be wrong with it?
--

[-Lost]

"Lee" <RE**************@cox.netwrote in message news:ev********@drn.newsguy.com...

-Lost said:

>>
"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...

>>Richard Maher said the following on 4/13/2007 10:35 PM:
Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

Well, um, to quote you, "Did you test that?" : )

Did you? What seems to be wrong with it?

You know, I did. I also however, forgot to test in something other than Firefox.

I wonder why Firefox will not allow multiple spaces in an alert() then?

-Lost

[Evertjan.]

Randy Webb wrote on 14 apr 2007 in comp.lang.javascript:

Richard Maher said the following on 4/13/2007 10:35 PM:

>Hi,

Can anyone please show me a regular expression (or function or other)
for padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is
the largest string I have to pad out, and then I concatenate a
substring of that to my source string so that it ends up the right
size. This all works well but, if possible, I'd like a more
generic/elegant approach to manufacturing N spaces. Is the a regular
expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

<script type='text/javascript'>

// Without looping, with cutoff of too long strings
// IE7 and FF tested

function fixedLength(s,n){
n = (n<0) ?0 :n
s = s.substr(0,n);
var a = [];
a.length = n - s.length + 1;
return s + a.join(' ');
};

// testing:

a = fixedLength('test',12);
alert('>' + a + '< ' + a.length);

a = fixedLength('test',3);
alert('>' + a + '< ' + a.length);

a = fixedLength('test',-22);
alert('>' + a + '< ' + a.length);

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

[Randy Webb]

-Lost said the following on 4/14/2007 12:31 AM:

"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...

>Richard Maher said the following on 4/13/2007 10:35 PM:

>>Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

Well, um, to quote you, "Did you test that?" : )

Yes I did. And I get the results I expected in FF, IE and Opera. Did
*you* test it? And if you got different results, what were they and what
OS/Browser gave them? There is a reason I added the and < though.
--
Randy
Chance Favors The Prepared Mind
comp.lang.javascript FAQ - http://jibbering.com/faq/index.html
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[-Lost]

"Randy Webb" <Hi************@aol.comwrote in message
news:Se********************@giganews.com...

-Lost said the following on 4/14/2007 12:31 AM:

>"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...

>>Richard Maher said the following on 4/13/2007 10:35 PM:
Hi,

Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?
var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

Well, um, to quote you, "Did you test that?" : )

Yes I did. And I get the results I expected in FF, IE and Opera. Did *you* test it? And
if you got different results, what were they and what OS/Browser gave them? There is a
reason I added the and < though.

In Firefox 1.5.0.11 on Windows XP SP2, I get:

>test < (notice only one space)

As Lee suggested, I ended up testing in Opera and Internet Explorer (6, not 7) and noticed
that they both allow spaces in the alert() string. Firefox will not give me more than
one.

I actually remembered coming across this situation before, that is why when I saw it, I
tested it in Firefox (to make sure I remembered it correctly), noticed it did not pad
spaces, then posted. Sorry for not checking it more thoroughly. Then my question would
have just been, "Hey, why does that not work in Firefox? At least for me..."

Thanks!

-Lost

[Randy Webb]

-Lost said the following on 4/14/2007 11:18 AM:

"Randy Webb" <Hi************@aol.comwrote in message
news:Se********************@giganews.com...

>-Lost said the following on 4/14/2007 12:31 AM:

>>"Randy Webb" <Hi************@aol.comwrote in message
news:4L********************@giganews.com...
Richard Maher said the following on 4/13/2007 10:35 PM:
Hi,
>
Can anyone please show me a regular expression (or function or other) for
padding out a string to a fixed number of bytes?
>
At the moment I've got a var initialized to N spaces, where 'N' is the
largest string I have to pad out, and then I concatenate a substring of that
to my source string so that it ends up the right size. This all works well
but, if possible, I'd like a more generic/elegant approach to manufacturing
N spaces. Is the a regular expression to returning {N}*aString?
var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")
Well, um, to quote you, "Did you test that?" : )

Yes I did. And I get the results I expected in FF, IE and Opera. Did *you* test it? And
if you got different results, what were they and what OS/Browser gave them? There is a
reason I added the and < though.

In Firefox 1.5.0.11 on Windows XP SP2, I get:

>test < (notice only one space)

As Lee suggested, I ended up testing in Opera and Internet Explorer (6, not 7) and noticed
that they both allow spaces in the alert() string. Firefox will not give me more than
one.

Testing it further in IE and FF2.0 I get some results that I wouldn't
expect where the length of testString is 16 instead of 12 (and I know
why) so I should tested it more thoroughly. Oh well :)

--
Randy
Chance Favors The Prepared Mind
comp.lang.javascript FAQ - http://jibbering.com/faq/index.html
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[Richard Maher]

Hi Evertjan,

"Evertjan." <ex**************@interxnl.netwrote in message
news:Xn********************@194.109.133.242...

Randy Webb wrote on 14 apr 2007 in comp.lang.javascript:

Richard Maher said the following on 4/13/2007 10:35 PM:

Hi,

Can anyone please show me a regular expression (or function or other)
for padding out a string to a fixed number of bytes?

At the moment I've got a var initialized to N spaces, where 'N' is
the largest string I have to pad out, and then I concatenate a
substring of that to my source string so that it ends up the right
size. This all works well but, if possible, I'd like a more
generic/elegant approach to manufacturing N spaces. Is the a regular
expression to returning {N}*aString?

var lengthRequired = 12
var testString = "test"
while (testString.length<lengthRequired){
testString += " ";
}
alert(">" + testString + "<")

<script type='text/javascript'>

// Without looping, with cutoff of too long strings
// IE7 and FF tested

function fixedLength(s,n){
n = (n<0) ?0 :n
s = s.substr(0,n);
var a = [];
a.length = n - s.length + 1;
return s + a.join(' ');
};

// testing:

a = fixedLength('test',12);
alert('>' + a + '< ' + a.length);

a = fixedLength('test',3);
alert('>' + a + '< ' + a.length);

a = fixedLength('test',-22);
alert('>' + a + '< ' + a.length);

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

I like it. I'll use the Array length/join(' ') at initialize time as a sort
of space$() function to preallocate a maximum space-filled string, but then
stick to substringing out of that the number of space bytes I need for
padding. Thanks for the help.

Cheers Richard Maher

[Evertjan.]

Richard Maher wrote on 15 apr 2007 in comp.lang.javascript:

I wrote:

>function fixedLength(s,n){
n = (n<0) ?0 :n
s = s.substr(0,n);
var a = [];
a.length = n - s.length + 1; // never negative <--------------
return s + a.join(' ');
};

>
I like it. I'll use the Array length/join(' ') at initialize time as a
sort of space$() function to preallocate a maximum space-filled
string, but then stick to substringing out of that the number of space
bytes I need for padding.

Did some testing:

alert(new Array(17).length); // 17
alert(new Array(17).join('?').length); // 16

alert(new Array('17').length); // 1 <-----------------
alert(new Array('17').join('?').length); // 2 <-------------

alert(new Array(0).length); // 0
alert(new Array(0).join('?').length); // 0
// alert(new Array(-3).length); // error
function newArray(n){
var a = [];
a.length = n;
return a;
}

alert(newArray(17).length); // 17
alert(newArray(17).join('?').length); // 16

alert(newArray('17').length); // 17 <------------------
alert(newArray('17').join('?').length); // 16 <-------------

alert(newArray(0).length); // 0
alert(newArray(0).join('?').length); // 0
// alert(newArray(-3).length); // error

;-)

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

[Dr J R Stockton]

In comp.lang.javascript message <yZydnS--i_vh5r3bnZ2dnUVZ_qemnZ2d@comcas
t.com>, Sat, 14 Apr 2007 02:58:34, -Lost <mi*********@comcast.net>
posted:

>
I wonder why Firefox will not allow multiple spaces in an alert() then?

Because it is out-of-date? Here, FF 2.0.0.3 shows multiple spaces,
though they are difficult to count.
Noting Evertjan's reply -
<URL:http://www.merlyn.demon.co.uk/js-misc0.htm#MLSshows how to make a
padding-string of any length L by using only O(log2(L)) concatenations.

--
(c) John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.
<URL:http://www.merlyn.demon.co.uk/TP/BP/Delphi/&c., FAQqy topics & links;
<URL:http://www.merlyn.demon.co.uk/clpb-faq.txt RAH Prins : c.l.p.b mFAQ;
<URL:ftp://garbo.uwasa.fi/pc/link/tsfaqp.zipTimo Salmi's Turbo Pascal FAQ.

[ron.h.hall]

On Apr 15, 9:53 am, Dr J R Stockton <[e-mail]:

In comp.lang.javascript message <yZydnS--i_vh5r3bnZ2dnUVZ_qemnZ2d@comcas
t.com>, Sat, 14 Apr 2007 02:58:34, -Lost <[e-mail]>
posted:

I wonder why Firefox will not allow multiple spaces in an alert() then?

Because it is out-of-date? Here, FF 2.0.0.3 shows multiple spaces,
though they are difficult to count.

Noting Evertjan's reply -
<URL:http://www.merlyn.demon.co.uk/js-misc0.htm#MLSshows how to make a
padding-string of any length L by using only O(log2(L)) concatenations.

Not as given though. "&&" appears where "&" was likely the intended
operator.

--
../rh

[Dr J R Stockton]

In comp.lang.javascript message <11**********************@b75g2000hsg.go
oglegroups.com>, Sun, 15 Apr 2007 12:54:39, ro********@gmail.com posted:

>On Apr 15, 9:53 am, Dr J R Stockton <[e-mail]:

>Noting Evertjan's reply -
<URL:http://www.merlyn.demon.co.uk/js-misc0.htm#MLSshows how to make a
padding-string of any length L by using only O(log2(L)) concatenations.

Not as given though. "&&" appears where "&" was likely the intended
operator.

Thank you. I think that must be a typo on transferring from the
"development" version - you'll have noted that the result is not
affected, only the speed. Corrected.

--
(c) John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.
Web <URL:http://www.merlyn.demon.co.uk/- FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

[ron.h.hall]

On Apr 16, 5:14 am, Dr J R Stockton <[e-mail]:

In comp.lang.javascript message <[e-mail]
oglegroups.com>, Sun, 15 Apr 2007 12:54:39, [e-mail] posted:

On Apr 15, 9:53 am, Dr J R Stockton <[e-mail]:

Noting Evertjan's reply -
<URL:http://www.merlyn.demon.co.uk/js-misc0.htm#MLSshows how to make a
padding-string of any length L by using only O(log2(L)) concatenations.

Not as given though. "&&" appears where "&" was likely the intended
operator.

Thank you. I think that must be a typo on transferring from the
"development" version - you'll have noted that the result is not
affected, only the speed. Corrected.

Yes, I could have been clearer that I was making reference only to the
failure on O(log2(L) efficiency.

While your BigCat function is instructive with regard to recursion, I
personally prefer to see the use of Array.prototype.join mechanism for
facilitating padding operations, both for simplicity and efficiency
reasons.

I've generally also found that use of built-in functions where
possible (executing as native code, and presumably with efficient
algorithms) are generally considerably faster than script-implemented
alternatives.

--
../rh