Please, give me an advise how to make a search of a number in xml-file (as3.0)

My response was based on your question of finding numbers anywhere in the data of an xml file.  If you know the data is numeric data and the names of the nodes containing that data, then you do not have to check characters and can just check the number data using the string values....

function searchXMLFile(Event:MouseEvent):void
{
          searchDisplay.text = "";
          var pageList:XMLList = xmlFileToSearch.receipt.number;
          searchDisplay.text = "false";
   
          for (var i:int = 0; i < pageList.length(); i++)
          {

               if(pageList == searchInput.text){
                   searchDisplay.text = "true";
               }

          }
}

Even if you were looking for individual numeric characters in your previous code you would always have ended up with a false output due to have the "false" line always canceling the true line...

                              if (t.toString().indexOf(m_sSearchTerm) != -1)

                              {

                                        searchDisplay.text = "true";

                              }

                              searchDisplay.text = "false";  // this will always overwrite the textfield