Entry

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

Jan 10th, 2004 20:35
Knud van Eeden,

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--- Knud van Eeden --- 04 January 2004 - 05:57 pm --------------------

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

---

Steps: Overview:

 1. -Create a new Java (stand alone) application

 2. -Fill in the following code

--- cut here ---------------------------------------------------------

import java.io.*;

//

 class CLASSStringConvertInfixToSuffix {

  private String expressionS;

  private String tabletokenS;

  private String tableinputS;

  private String tablestackS;

  private String stackS;

  private String kexpressionS;

  private String kstackS;

  private String resultS;

  private int expressionI;

  private int stackI;

  private int posI;

  private int priorityinputI;

  private int prioritystackI;

  private int I;

 // constructor for this class

 public CLASSStringConvertInfixToSuffix( String expressionS )

 {

  this.expressionS = expressionS;

  tabletokenS = "#-+/*^abcdefghijklmnopqrstuvwxyz0123456789()";

  tableinputS = "03344599999999999999999999999999999999999992";

  tablestackS = "03344599999999999999999999999999999999999929";

  stackS = "";

  kexpressionS = "";

  kstackS = "";

  resultS = "";

  expressionI = 0 - 1;

  stackI = 0 - 1;

  posI = -1;

  priorityinputI = -1;

  prioritystackI = -1;

  I = 0;

  stackI = stackI + 1;

  stackS = "#";

 }

 // destructor for this class

 protected void finalize() {

 }

 //

 public String FNStringConvertInfixToPrefixS() {

  do

  {

   expressionI = expressionI + 1;

   kexpressionS = expressionS.substring( expressionI, expressionI + 
1 );

   posI = tabletokenS.indexOf( kexpressionS, 0 );

   if ( posI == -1 ) {

    System.out.println( kexpressionS + " not found in tabletokenS " + 
tabletokenS );

    return( "error" );

   }

   priorityinputI = Integer.valueOf( tableinputS.substring( posI, posI 
+ 1 ) ).intValue();

   kstackS = stackS.substring( 0, 1 );

   posI = tabletokenS.indexOf( kstackS, 0 );

   if ( posI < 0 ) {

    System.out.println( kstackS + " not found in tabletokenS " + 
tabletokenS );

    return( "error" );

   }

   prioritystackI = Integer.valueOf( tablestackS.substring( posI, posI 
+ 1 ) ).intValue();

   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 ) {

      System.out.println( kstackS + " not found in tabletokenS " + 
tabletokenS );

      return( "error" );

     }

     prioritystackI = Integer.valueOf( tablestackS.substring( posI, 
posI + 1 ) ).intValue();

    } 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.equals( "#" ) ) && ( !kstackS.equals( "(" ) ) && ( !
kstackS.equals( ")" ) ) ) {

    resultS = resultS + kstackS;

   }

  } while ( I < ( stackS.length() - 1 ) );

  return( resultS );

 }

}

 //

 class CLASSStringConvertInfixToSuffixMain {

  public static void main( String args[] ) throws IOException {

   String infixS = "((2*3)^6+(4*5)+(6*7))^7";

   BufferedReader kbd = new BufferedReader( new InputStreamReader( 
System.in ) );

   do {

    CLASSStringConvertInfixToSuffix OBJECTrpn = new 
CLASSStringConvertInfixToSuffix( infixS );

    System.out.println( "infix = " + infixS );

    System.out.println( "suffix = " + 
OBJECTrpn.FNStringConvertInfixToPrefixS() );

    System.out.println( "Type in a new infix String (type Q to quit), 
for example (3+4)*5+6-7 ");

    try {

     infixS = kbd.readLine();

    }

    catch ( Exception e ) {

     System.out.println( "an input error occurred" );

    }

    if ( infixS.equals( "" ) ) {

     infixS = "(3+4)*5+6-7";

    }

   } while ( !infixS.toLowerCase().equals( "q" ) );

  }

 }


--- 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:

Compiled successfully as a console application in:

- SUN Java command line compilers javac.exe and java.exe

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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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