What would you use to zero pad a number in Flex/AS3?

Question

Duplicate of this one.

What would you use to pad zeroes to the left of a number in Flex/AS3?

Is there an equivalent to printf or NumberFormat that does this?

I'm looking for the nicest implementation of this or something similar:

public function zeroPad(number:int, width:int):String {
    // number = 46, width = 4 would return "0046"
}

Answer 1

public function zeroPad(number:int, width:int):String {
   var ret:String = ""+number;
   while( ret.length < width )
       ret="0" + ret;
   return ret;
}

Answer 2

Performance-wise, I prefer using a String constant and substr, like this:

package {
    public class Helper {
        private static const _ZEROS:String = "0000000000000000000000000000000000000000"; // 40 zeros, shorten/expand as you wish

        /*
         * f: positive integer value
         * z: maximum number of leading zeros of the numeric part (sign takes one extra digit)
         */
        public static function uint_Zeropadded(f:uint, z:int = 0):String {
            var result:String = f.toString();
            while (result.length < z)
                result = _ZEROS.substr(0, z - result.length) + result;
            return result;
        }
    }
}

The String constant has very little footstamp compared to the performance draw-backs of extending the string one by one digit numerous times. In most cases (up to 40 zeros in this example) number of instructions is the same for all calls.

Answer 3

Phil's variant as an elegant recursion:

public function zeroPad (number:String, width:int):String {
    if (number.length < width)
        return "0" + zeroPad(number, width-1);
    return number;
}

I don't know of its performance on AS3 but it sure looks cooler! :-)

Answer 4

public static function getFormatedValue(num:Number, roundDecimalPlace:Number=2, showLastZerosInDecimalPlaces:Boolean = false, decimalSeparator:String=".", thousandsSeparator:String=",", currency:String="$"):String
{
  //assigns true boolean value to neg in number less than 0
  var neg:Boolean = (num < 0);

  //make the number positive for easy conversion
  num = Math.abs(num)

  var roundedAmount:String = String(num.toFixed(roundDecimalPlace));

  //split string into array for dollars and cents
  var amountArray:Array = roundedAmount.split(".");
  var dollars:String = amountArray[0]
  var cents:String = amountArray[1]

  //create dollar amount
  var dollarFinal:String = ""
  var i:int = 0
  for (i; i < dollars.length; i++)
  {
    if (i > 0 && (i % 3 == 0 ))
    {
      dollarFinal = thousandsSeparator + dollarFinal;
    }

    dollarFinal = dollars.substr( -i -1, 1) + dollarFinal;
  }       

  //create Cents amount and zeros if necessary
  var centsFinal:String;

  if(showLastZerosInDecimalPlaces)
  {
    centsFinal = String(cents);

    var missingZeros:int = roundDecimalPlace - centsFinal.length;

    if (centsFinal.length < roundDecimalPlace)
    {
      for (var j:int = 0; j < missingZeros; j++) 
      {
        centsFinal += "0";
      }
    }
  }
  else
  {
    if(Number(cents) != 0)
    {
      centsFinal = String(String(Number("0."+cents)).split(".")[1]);
    }
    else
    {
      roundDecimalPlace = 0;
    }
  }

  var finalString:String = ""

  if (neg)
  {
    finalString = "-"+currency + dollarFinal
  } else
  {
    finalString = currency + dollarFinal
  }

  if(roundDecimalPlace > 0)
  {
    finalString += decimalSeparator + centsFinal;
  } 

  return finalString;
}

Answer 5

Very short example of zero padding routine (AS2)...

    Convert = function(Minutes) {
       return ('00'+String(int(Minutes/60)%24)).substr(-2,2);
    }

Answer 6

/** 
 * originally by Chris Agiasotis @ http://agitatedobserver.com/as3-currency-formatter/
 * improved by Joseph Balderson @ http://www.joeflash.ca
 */
package
{
    public class CurrencyFormat
    {
        public function CurrencyFormat(){ }

        public function getCurrency(num:Number,
                    decimalSeparator:String=".",
                    decimalPlace:Number=2,
                    currency:String="$",
                    thousandsSeparator:String=","
                ):String
        {
            //assigns true boolean value to neg in number less than 0
            var neg:Boolean = (num < 0);

            //make the number positive for easy conversion
            num = Math.abs(num)

            var roundedAmount:String = String(num.toFixed(decimalPlace));

            //split string into array for dollars and cents
            var amountArray:Array = roundedAmount.split(".");
            var dollars:String = amountArray[0]
            var cents:String = amountArray[1]

            //create dollar amount
            var dollarFinal:String = ""
            var i:int = 0
            for (i; i < dollars.length; i++)
            {
                if (i > 0 && (i % 3 == 0 ))
                {
                    dollarFinal = thousandsSeparator + dollarFinal;
                }

                dollarFinal = dollars.substr( -i -1, 1) + dollarFinal;
            }   

            //create Cents amount and zeros if necessary
            var centsFinal:String = String(cents);

            var missingZeros:int = decimalPlace - centsFinal.length;

            if (centsFinal.length < decimalPlace)
            {
                for (var j:int = 0; j < missingZeros; j++) 
                {
                    centsFinal += "0";
                }
            }

            var finalString:String = ""

            if (neg)
            {
                finalString = "-"+currency + dollarFinal
            } else
            {
                finalString = currency + dollarFinal
            }

            if(decimalPlace > 0)
            {
                finalString += decimalSeparator + centsFinal;
            } 

            return finalString;
        }
    }
}

Answer 7

I do maintain a printf in AS3: Unfortunately stack overflow won't let me post links, but if the google code's project name is printf-as3

Feedback is always welcome.

--

http://code.google.com/p/printf-as3/

Answer 8

A very compact solution:

public function zeroPad(s:String,pad:int):String {
    for(;s.length<pad;s='0'+s);
    return s;
}