Hi guys, I need to change an integer to a minimum length of 3 places eg 1 would be 001. This is required for a peice of hardware I have built for dimming which works from 000 to 255. Any ideas on how to change the integer? I thought the java command setLength() would work but pronto won't have it. Thanks

try:
while ((a&"").length<3) a="0"&a;

the a+"" should convert a to type string since to do the concatenation it must be a string. Adding an empty string ("") to a string does not change the original string.

I have not tested the above.

Unfortunatly that doesnt seem to do the trick, no zeros have been appended.

var dimming ;
If ( dimming = 0 ) { dimming = 000 ; };

I already use that line but it doesnt solve the problem with numbers 1 to 99.

chudson,

In your first post, you mention java. It is not java, it is javascript. Java and javascript bare some similarities but they are completely different languages.

If you know the length you want, it is quicker to pre-build a string of 0's and use substring.

function zeroFill3 (value)
{
var ret = '000' + value;
var l = ret.length;
return ret.substring(l - 3,l);
}

If you don't know the length you need, use a loop to build out string. Barry's example may be quicker but the code below is what I used at one time for EscientPronto.

function zeroFillToPrecision(value,precision)
{
precision=0 - precision;
value=Math.abs(0-value);
var strValue = '' + value;
var valueLen = strValue.length;
if (valueLen >= precision) /* truncate length to precision.*/
return strValue.substring(valueLen-precision);
else
{
var ret = '';
for (var i=0;i {
ret += '0';
} // for
ret += strValue;
return ret.substring(ret.length-precision);
} // else
}

My pseudo code technique for this sort of issue has been:

last3characters( "00" || stringValueOf( number) )

"||" is my shorthand for string concatenation.

In interpreted languagues this is straight forward and relatively quick.

(This is simply a less general, single line version of Lyndel's scheme.)

Wow using an or to concatenate strings. Never seen this. I'm amazed it works, have o try it.

buzz but if I'm not mistaken, in your case:

"00" || stringValueOf(2) = "002"
"00" || stringValueOf(12) = "0012"

While with Lyndel's code the result of the first is "002" and the second is "012".

Also is the method stringValueOf necessary? I believe that in javascript : ""+12 = "12".

chudson, wait, you need to send those values as integers (so in hex 0x00 - 0xff) or in ascii? Plese make it more celar.

Thanks Buzz... Yes, I noticed the correct spelling. Much appreciated.

What is stringValueOf() function?

BluPhenix,

Like Barry Gordon, I have too many computer languages circulating in my brain.

"||" in some languages is string concatenation, in others it could be an Exclusive OR or a simple OR.

In JavaScript string concatenation is "+". I don't like the "+" syntax because it is too easy to confuse with arithmetic.

This is why I tried to define my terms in the previous post. Because of where I've come from "||" is what I use for string concatenation in my brain. Mercifully, it usually comes out as "+" when I'm typing JavaScript.

What is stringValueOf() ????

I guess is some function from another language :). Don't be to troubled by it :)

Anyhow, buzz's way in javascript is: "00"+number :).

But this exposes the issue i posted and that Lyndel's code solves ("0012") ...

Yes, "00" + myNumber will be "0012" if myNumber has integral value of 12. That is exactly why I posted my functions.

In the Escient protocol, you need zero-padded lengths of 2, 3, 4, and 5. I specifically have 4 different functions that do this versus the looping one as the string concat with specific length is much quicker than doing the looping to build a string of '0's with specific precision.

Here is what I use (tested too)

function padIt (a,b) {c=a+""; while(c.length < b) {c="0"+c;} return c;}

for those not Prontoscript fluent:
c=a+""; causes c to be converted to a string in case 'a' was an integer and is necessary for the while test to work correctly as an integer has an undefined length. If a was already a string then concatenating it with an empty string does nothing

In Javascript the Plus(+) operator is overloaded and takes on two different operations; addition and concatenation. The overloading is resolved by the context in which the operator is used. This can run into unexpected issues when one wants to build a string that terminates in an integer number. For example

label="Item_";
System.print(label); produces "Item_"
label="Item_"+1;
System.print(label); produces "Item_1"
label="Item_"+1+2;
System.print(label); produces "Item_12"
label="Item_"+(1+2);
System.print(label); produces "Item_3"

The (1+2) causes that term to be evaluted arithmetically since the "(" starts a new context. In the case "Item_"+1+2 the evaluation proceeds from left to right with the left side providing the context. Ergo evaluating "Item_"+1 causes "1" to be converted to a string and then concatenated to "Item_" yielding "Item_1".

The two most bothersome attributes of Javascript (to me) are the fact that symbols are case sensitive and the overloading of "+". I was trained on languages where symbols are case insensitive. Most of my semantic errors in Javascript code I write are due to the symbols being case sensitive in Javascript; since most syntax checkers will not catch that

Different people, different tastes :)

I actually like the overloading of the + operator, I simply take it that it adds to something. In the case of 5+3 it adds 3 to 5 in the case of "number"+1 it adds 1 to number.

Maybe it's easyer to remember this way: if the most left value of a variable is a string then the whole variable is a string.

So Barry's c=a+"" would have the form of c=""+a in my code. To not forget this i even do:
myVariable=""+1+variable1+ariable2+"string"+"\r" so i know it is a string as soon I look over the = sign.

Barry if you don't yet, use JSLint (the good parts) it let's you define "members" (methods and properties) of objects and checks the code against the list you provided. It's case sensitive and if it finds a properts or method that is different from your list it alerts you. I can't work without it any more.