Is there a way to format a String in Flex

Question

Is it possible to do something like this:

var s:String = format("%20d %-10s %s", time, type, message);

In languages like C, C++, C#, Python, and Perl there is something similar to my example, but I can't seem to find it for Flex.

I don't want to create special class Formatter for every string that I want to format.

Answer 1

You probably are looking for mx.utils.StringUtil.substitute(). Works similar to .NET String.Format().

For Example:

StringUtil.substitute("Hello {0}", ["World"]);

Adobe Livedocs for StringUtil class

Answer 2

Found this script that implements sprintf - and that's exactly what I was looking for. Thanks to Manish Jethani!

/*  sprintf(3) implementation in ActionScript 3.0.
 *
 *  Author:  Manish Jethani ([e-mail])
 *  Date:    April 3, 2006
 *  Version: 0.1
 *
 *  Copyright (c) 2006 Manish Jethani
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),
 *  to deal in the Software without restriction, including without limitation
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
 *  and/or sell copies of the Software, and to permit persons to whom the
 *  Software is furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *  DEALINGS IN THE SOFTWARE.  
 */

package
{

/*  sprintf(3) implementation in ActionScript 3.0.
 *
 *  http://www.die.net/doc/linux/man/man3/sprintf.3.html
 *
 *  The following flags are supported: '#', '0', '-', '+'
 *
 *  Field widths are fully supported.  '*' is not supported.
 *
 *  Precision is supported except one difference from the standard: for an
 *  explicit precision of 0 and a result string of "0", the output is "0"
 *  instead of an empty string.
 *
 *  Length modifiers are not supported.
 *
 *  The following conversion specifiers are supported: 'd', 'i', 'o', 'u', 'x',
 *  'X', 'f', 'F', 'c', 's', '%'
 *
 *  Report bugs to [e-mail]
 */
public function sprintf(format:String, ... args):String
{
 var result:String = "";

 var length:int = format.length;
 for (var i:int = 0; i < length; i++)
 {
  var c:String = format.charAt(i);

  if (c == "%")
  {
   var pastFieldWidth:Boolean = false;
   var pastFlags:Boolean = false;

   var flagAlternateForm:Boolean = false;
   var flagZeroPad:Boolean = false;
   var flagLeftJustify:Boolean = false;
   var flagSpace:Boolean = false;
   var flagSign:Boolean = false;

   var fieldWidth:String = "";
   var precision:String = "";

   c = format.charAt(++i);

   while (c != "d"
    && c != "i"
    && c != "o"
    && c != "u"
    && c != "x"
    && c != "X"
    && c != "f"
    && c != "F"
    && c != "c"
    && c != "s"
    && c != "%")
   {
    if (!pastFlags)
    {
     if (!flagAlternateForm && c == "#")
      flagAlternateForm = true;
     else if (!flagZeroPad && c == "0")
      flagZeroPad = true;
     else if (!flagLeftJustify && c == "-")
      flagLeftJustify = true;
     else if (!flagSpace && c == " ")
      flagSpace = true;
     else if (!flagSign && c == "+")
      flagSign = true;
     else
      pastFlags = true;
    }

    if (!pastFieldWidth && c == ".")
    {
     pastFlags = true;
     pastFieldWidth = true;

     c = format.charAt(++i);
     continue;
    }

    if (pastFlags)
    {
     if (!pastFieldWidth)
      fieldWidth += c;
     else
      precision += c;
    }

    c = format.charAt(++i);
   }

   switch (c)
   {
   case "d":
   case "i":
    var next:* = args.shift();
    var str:String = String(Math.abs(int(next)));

    if (precision != "")
     str = leftPad(str, int(precision), "0");

    if (int(next) < 0)
     str = "-" + str;
    else if (flagSign && int(next) >= 0)
     str = "+" + str;

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else if (flagZeroPad && precision == "")
      str = leftPad(str, int(fieldWidth), "0");
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "o":
    var next:* = args.shift();
    var str:String = uint(next).toString(8);

    if (flagAlternateForm && str != "0")
     str = "0" + str;

    if (precision != "")
     str = leftPad(str, int(precision), "0");

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else if (flagZeroPad && precision == "")
      str = leftPad(str, int(fieldWidth), "0");
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "u":
    var next:* = args.shift();
    var str:String = uint(next).toString(10);

    if (precision != "")
     str = leftPad(str, int(precision), "0");

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else if (flagZeroPad && precision == "")
      str = leftPad(str, int(fieldWidth), "0");
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "X":
    var capitalise:Boolean = true;
   case "x":
    var next:* = args.shift();
    var str:String = uint(next).toString(16);

    if (precision != "")
     str = leftPad(str, int(precision), "0");

    var prepend:Boolean = flagAlternateForm && uint(next) != 0;

    if (fieldWidth != "" && !flagLeftJustify
      && flagZeroPad && precision == "")
     str = leftPad(str, prepend
       ? int(fieldWidth) - 2 : int(fieldWidth), "0");

    if (prepend)
     str = "0x" + str;

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else
      str = leftPad(str, int(fieldWidth));
    }

    if (capitalise)
     str = str.toUpperCase();

    result += str;
    break;

   case "f":
   case "F":
    var next:* = args.shift();
    var str:String = Math.abs(Number(next)).toFixed(
      precision != "" ?  int(precision) : 6);

    if (int(next) < 0)
     str = "-" + str;
    else if (flagSign && int(next) >= 0)
     str = "+" + str;

    if (flagAlternateForm && str.indexOf(".") == -1)
     str += ".";

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else if (flagZeroPad && precision == "")
      str = leftPad(str, int(fieldWidth), "0");
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "c":
    var next:* = args.shift();
    var str:String = String.fromCharCode(int(next));

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "s":
    var next:* = args.shift();
    var str:String = String(next);

    if (precision != "")
     str = str.substring(0, int(precision));

    if (fieldWidth != "")
    {
     if (flagLeftJustify)
      str = rightPad(str, int(fieldWidth));
     else
      str = leftPad(str, int(fieldWidth));
    }

    result += str;
    break;

   case "%":
    result += "%";
   }
  }
  else
  {
   result += c;
  }
 }

 return result;
}

}

// Private functions

function leftPad(source:String, targetLength:int, padChar:String = " "):String
{
 if (source.length < targetLength)
 {
  var padding:String = "";

  while (padding.length + source.length < targetLength)
   padding += padChar;

  return padding + source;
 }

 return source;
}

function rightPad(source:String, targetLength:int, padChar:String = " "):String
{
 while (source.length < targetLength)
  source += padChar;

 return source;
}

Answer 3

The printf-as3 project sounds like it should fit your needs