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Language: Computer: JavaScript: Simple: How to convert infix to suffix? [Bracket]

Apr 7th, 2008 23:40
ha mo, Knud van Eeden,


----------------------------------------------------------------------
--- Knud van Eeden --- 11 January 2004 - 08:33 am --------------------
Language: Computer: JavaScript: Simple: How to convert infix to 
suffix? [Bracket]
---
Steps: Overview:
 1. -Create a new JavaScript application
 2. -Fill in the following code
--- cut here ---------------------------------------------------------
<SCRIPT LANGUAGE = "JavaScript">
<!--
<!-- library: math: convert: string: infix: suffix [kn, ri, su, 11-01-
2004  7:30:56]
function FNStringConvertInfixToPrefixS( expressionS ) {
 // e.g. <HTML>
 // e.g.  <BODY onLoad=' PROCMessage( FNStringConvertInfixToPrefixS
( "((2*3)^6+(4*5)+(6*7))^7" ) ); // gives e.g. 23*6^45*+67*+7^'>
 // e.g.  </BODY>
 // e.g. </HTML>
 var tabletokenS = "#-+/*^abcdefghijklmnopqrstuvwxyz0123456789()";
 var tableinputS = "03344599999999999999999999999999999999999992";
 var tablestackS = "03344599999999999999999999999999999999999929";
 var stackS = "";
 var kexpressionS = "";
 var kstackS = "";
 var resultS = "";
 var expressionI = 0 - 1;
 var stackI = 0 - 1;
 var posI = -1;
 var priorityinputI = -1;
 var prioritystackI = -1;
 var I = 0;
 var stackI = stackI + 1;
 var stackS = "#";
 do
 {
  expressionI = expressionI + 1;
  kexpressionS = expressionS.substring( expressionI, expressionI + 1 );
  posI = tabletokenS.indexOf( kexpressionS );
  if ( posI == -1 ) {
   alert( kexpressionS + " not found in tabletokenS " + tabletokenS );
   return( "error" );
  }
  priorityinputI = parseInt( tableinputS.substring( posI, posI + 1 ) );
  kstackS = stackS.substring( 0, 1 );
  posI = tabletokenS.indexOf( kstackS );
  if ( posI < 0 ) {
   alert( kstackS + " not found in tabletokenS " + tabletokenS );
   return( "error" );
  }
  prioritystackI = parseInt( tablestackS.substring( posI, posI + 1 ) );
  if ( priorityinputI > prioritystackI ) {
   stackS = kexpressionS + stackS;
  }
  else {
   do {
    if ( ( kstackS.charAt( 0 ) != '(' ) && ( kstackS.charAt( 0 ) !
= ')' ) ) {
     resultS = resultS + kstackS;
    }
    stackS = stackS.substring( 1, stackS.length );
    kstackS = stackS.substring( 0, 1 );
    posI = tabletokenS.indexOf( kstackS, 0 );
    if ( posI < 0 ) {
     alert( kstackS + " not found in tabletokenS " + tabletokenS );
     return( "error" );
    }
    prioritystackI = parseInt( tablestackS.substring( posI, posI + 
1 ) );
   } while ( priorityinputI <= prioritystackI );
   stackS = kexpressionS + stackS;
  }
 } while ( expressionI < ( expressionS.length - 1 ) );
 I = 0 - 1;
 do {
  I = I + 1;
  kstackS = stackS.substring( I, I + 1 );
  if ( ( kstackS.charAt( 0 ) != '#' ) && ( kstackS.charAt( 0 ) !
= '(' ) && ( kstackS.charAt( 0 ) != ')' ) ) {
   resultS = resultS + kstackS;
  }
 } while ( I < ( stackS.length - 1 ) );
 return( resultS );
}
// -->
</SCRIPT>
--- cut here ---------------------------------------------------------
 3. -Run this code
     That should show:
      ((2*3)^6+(4*5)+(6*7))^7
      resultS is 23*6^45*+67*+7^
      which is respectively the infix and suffix representation.
 4. -Change expressionS to your own infix string
      e.g.
       expressionS = "(3+4)*5+6-7"
     and recompile for another example,
       e.g. that should show 34+5*6+7-
     ---
      Note:
       In order to keep it very simple and short in this 
implementation:
       1. Please take spaces away.
          so "(3+4)*5+6-7" is OK,
          but "( 3 + 4 ) * 5 + 6 - 7" is not.
       2. only single characters (like a, b, c, ..., 3, 4, 5, ...)
           so "a+b*c-d^f" is OK,
           but "alpha*beta+gamma" is not.
       3. the priorities should here be single numbers between 0 and 9
          (like 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
          in your tables.
       4. This program is a direct translation of the Dijkstra double
          priority algorithm (see below for the link and further 
description)
---
---
Note:
Successful run in browser Microsoft Explorer v6.
---
---
Internet: see also:
---
Algorithm: Expression: Infix: Convert: Postfix: Overview: How convert 
infix to postfix expression?
http://www.faqts.com/knowledge_base/view.phtml/aid/26071/fid/585
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