JavaScript DHTML/Development/Postfix Infix

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Infix to Postfix Conversion

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Infix to Postfix</title>
<style type="text/css">
.header{font-family:verdana,arial,helvetica; font-weight:bold; font-size:22pt; color:#003366; filter:DropShadow(color=#CCCCDD, offX=2, offY=2, positive=1); width:100%}
.form_in{background:#FCFCFF; border:#003366 solid 1px}
.text_box{font-weight:bold; background:#EFEFF5; border:#003366 solid 1px; height:20px}
.button{background:#CCCCDD; font-weight:bold; color:#003366; border:#003366 solid 1px; height:20px; cursor:hand}
.link{color:#003366}
.link:hover{color:#666699}
</style>
</head>
<body bgcolor="#FFFFFF">
<!--BEGIN INFIX TO POSTFIX JAVASCRIPT-->
<script language="JavaScript">
/*
  Infix to Postfix Conversion
  - Converts an Infix(Inorder) expression to Postfix(Postorder)
  - For eg. "1*2+3" converts to "12*3+"
  - Valid Operators are +,-,*,/
  - No Error Handling in this version
  JavaScript Implementation
  - CopyRight 2002 Premshree Pillai
  See algorithm at
  -http://www.qiksearch.ru/articles/cs/infix-postfix/index.htm
  Created : 28/08/02 (dd/mm/yy)
  Web : http://www.qiksearch.ru
  E-mail : qiksearch@rediffmail.ru
*/
function push_stack(stackArr,ele)
{
 stackArr[stackArr.length]=ele;
}
function pop_stack(stackArr)
{
 var _temp=stackArr[stackArr.length-1];
 delete stackArr[stackArr.length-1];
 stackArr.length--;
 return(_temp);
}
function isOperand(who)
{
 return(!isOperator(who)? true : false);
}
function isOperator(who)
{
 return((who=="+" || who=="-" || who=="*" || who=="/" || who=="(" || who==")")? true : false);
}
function topStack(stackArr)
{
 return(stackArr[stackArr.length-1]);
}
function isEmpty(stackArr)
{
 return((stackArr.length==0)? true : false);
}
/* Check for Precedence */
function prcd(char1,char2)
{
 var char1_index,char2_index;
 var _def_prcd="-+*/";
 for(var i=0; i<_def_prcd.length; i++)
 {
  if(char1==_def_prcd.charAt(i)) char1_index=i;
  if(char2==_def_prcd.charAt(i)) char2_index=i;
 }
 if(((char1_index==0)||(char1_index==1)) && (char2_index>1)) return false;
 else return true;
}
function InfixToPostfix(infixStr,postfixStr)
{
 var postfixStr=new Array();
 var stackArr=new Array();
 var postfixPtr=0;
 infixStr=infixStr.split("");
 for(var i=0; i<infixStr.length; i++)
 {
  if(isOperand(infixStr[i]))
  {
   postfixStr[postfixPtr]=infixStr[i];
   postfixPtr++;
  }
  else
  {
   while((!isEmpty(stackArr)) && (prcd(topStack(stackArr),infixStr[i])))
   {
    postfixStr[postfixPtr]=topStack(stackArr);
    pop_stack(stackArr);
    postfixPtr++;
   }
   if((!isEmpty(stackArr)) && (infixStr[i]==")"))
   {
    pop_stack(stackArr);
   }
   else
   {
    push_stack(stackArr,infixStr[i]);
   }
  }
 }
 while(!isEmpty(stackArr))
 {
  postfixStr[postfixStr.length]=topStack(stackArr);
  pop_stack(stackArr);
 }
 var returnVal="";
 for(var i=0; i<postfixStr.length; i++)
 {
  returnVal+=postfixStr[i];
 }
 return(returnVal);
}
</script>
<!--END INFIX TO POSTFIX JAVASCRIPT-->
<center><span class="header">Infix to Postfix Conversion</span></center>
<!--BEGIN FORM-->
<center>
<form name="input_form">
<table class="form_in" cellspacing="0" cellpadding="3">
 <tr bgcolor="#003366">
  <td><font face="verdana,arial,helvetica" size="-2" color="#CCCCDD">Infix Expression :</font></td>
  <td><font face="verdana,arial,helvetica" size="-2" color="#CCCCDD">Postfix Expression :</font></td>
  <td></td>
 </tr>
 <tr>
  <td><input type="text" name="infixVal" class="text_box" value=""></td>
  <td><input type="text" name="postfixVal" class="text_box" value=""></td>
  <td align="bottom"><input type="button" onClick="document.input_form.postfixVal.value=InfixToPostfix(document.input_form.infixVal.value,"arr")" value="Infix to Postfix" class="button"></td>
 </tr>
</table>
</form>
</center>
<!--END FORM-->
<table width="465" align="center"><tr><td>
 <font face="verdana,arial,helvetica" size="-1" color="#000000">
 This is the "JavaScript" Implementation of converting an Infix(Inorder) expression to Postfix(Postorder) expression.
 <br><br><a href="http://www.qiksearch.ru/articles/cs/infix-postfix/index.htm" class="link">Click here</a> for the algorithm used.
 <hr style="color:#003366; height:1px">
 &#169 2002 <a href="http://www.qiksearch.ru" class="link" title="Click here to visit Qiksearch.ru">Premshree Pillai</a>.
 </font>
</td></tr></table>
</body>
</html>



Postfix Evaluator

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Postfix Evaluator</title>
<style type="text/css">
.header{font-family:verdana,arial,helvetica; font-weight:bold; font-size:22pt; color:#0066CC; filter:DropShadow(color=#CCCCFF, offX=2, offY=2, positive=1); width:100%}
.form_in{background:#FFFFFF; border:#0066CC solid 1px}
.text_box{font-weight:bold; background:#EEEEFF; border:#0066CC solid 1px; height:20px}
.button{background:#0066CC; font-weight:bold; color:#FFFFFF; border:#0066CC solid 1px; height:20px; cursor:hand}
.link{color:#0066CC}
.link:hover{color:#0099FF}
</style>
</head>
<body bgcolor="#FFFFFF">
<!--BEGIN POSTFIX EVALUATOR JAVASCRIPT-->
<script language="JavaScript">
/*
  Postfix Evaluator
  - Evaluates a Postfix(Postorder) expression
  - For eg. "12*3+" results in 5
  - Valid Operators are +,-,*,/
  - No Error Handling in this version
  JavaScript Implementation
  - CopyRight 2002 Premshree Pillai
  See algorithm at
  -http://www.qiksearch.ru/articles/cs/postfix-evaluation/index.htm
  Created : 02/09/02 (dd/mm/yy)
  Web : http://www.qiksearch.ru
  E-mail : qiksearch@rediffmail.ru
*/
function push_stack(stackArr,ele)
{
 stackArr[stackArr.length]=ele;
}
function pop_stack(stackArr)
{
 var _temp=stackArr[stackArr.length-1];
 delete stackArr[stackArr.length-1];
 stackArr.length--;
 return(_temp);
}
function isOperand(who)
{
 return(!isOperator(who)? true : false);
}
function isOperator(who)
{
 return((who=="+" || who=="-" || who=="*" || who=="/" || who=="(" || who==")")? true : false);
}
function topStack(stackArr)
{
 return(stackArr[stackArr.length-1]);
}
function PostfixSubEval(num1,num2,sym)
{
 var returnVal;
 if(sym=="+")
  returnVal=num1+num2;
 if(sym=="-")
  returnVal=num1-num2;
 if(sym=="*")
  returnVal=num1*num2;
 if(sym=="/")
  returnVal=num1/num2;
 return(returnVal);
}
function PostfixEval(postfixStr)
{
 var stackArr=new Array();
 postfixStr=postfixStr.split("");
 for(var i=0; i<postfixStr.length; i++)
 {
  if(isOperand(postfixStr[i]))
  {
   push_stack(stackArr,postfixStr[i]);
  }
  else
  {
   var temp=parseFloat(topStack(stackArr));
   pop_stack(stackArr);
   var pushVal=PostfixSubEval(parseFloat(topStack(stackArr)),temp,postfixStr[i]);
   pop_stack(stackArr);
   push_stack(stackArr,pushVal);
  }
 }
 return(topStack(stackArr));
} 
</script>
<!--END POSTFIX EVALUATOR JAVASCRIPT-->
<center><span class="header">Postfix Evaluator</span></center>
<!--BEGIN FORM-->
<center>
<form name="input_form">
<table class="form_in" cellspacing="0" cellpadding="3">
 <tr bgcolor="#0066CC">
  <td><font face="verdana,arial,helvetica" size="-2" color="#FFFFFF">Postfix Expression :</font></td>
  <td><font face="verdana,arial,helvetica" size="-2" color="#FFFFFF">Result :</font></td>
  <td></td>
 </tr>
 <tr>
  <td><input type="text" name="postfixVal" class="text_box" value=""></td>
  <td><input type="text" name="resultVal" class="text_box" value=""></td>
  <td align="bottom"><input type="button" onClick="document.input_form.resultVal.value=PostfixEval(document.input_form.postfixVal.value)" value="Evaluate Postfix" class="button"></td>
 </tr>
</table>
</form>
</center>
<!--END FORM-->
<table width="485" align="center"><tr><td>
 <font face="verdana,arial,helvetica" size="-1" color="#000000">
 This JavaScript evaluates a Postfix(Postorder) expression.
 <br><br><a href="http://www.qiksearch.ru/articles/cs/postfix-evaluation/index.htm" class="link">Click here</a> for the algorithm used.
 <hr style="color:#003366; height:1px">
 &#169 2002 <a href="http://www.qiksearch.ru" class="link" title="Click here to visit Qiksearch.ru">Premshree Pillai</a>.
 </font>
</td></tr></table>
</body>
</html>



Postfix to Infix Conversion

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Postfix to Infix</title>
<style type="text/css">
.header{font-family:verdana,arial,helvetica; font-weight:bold; font-size:22pt; color:#0066CC; filter:DropShadow(color=#CCCCFF, offX=2, offY=2, positive=1); width:100%}
.form_in{background:#FFFFFF; border:#0066CC solid 1px}
.text_box{font-weight:bold; background:#EEEEFF; border:#0066CC solid 1px; height:20px}
.button{background:#0066CC; font-weight:bold; color:#FFFFFF; border:#0066CC solid 1px; height:20px; cursor:hand}
.link{color:#0066CC}
.link:hover{color:#0099FF}
</style>
</head>
<body bgcolor="#FFFFFF">
<!--BEGIN POSTFIX TO INFIX JAVASCRIPT-->
<script language="JavaScript">
/*
  Postfix to Infix Conversion
  - Converts a Postfix(Postorder) expression to Infix(Inorder)
  - For eg. "abc/+d-" converts to "a+b/c-d"
  - Valid Operators are +,-,*,/
  - No Error Handling in this version
  JavaScript Implementation
  - CopyRight 2002 Premshree Pillai
  Based on "Postfix Evaluator". See
  -http://www.qiksearch.ru/javascripts/postfix-evaluator.htm
  See algorithm at
  -http://www.qiksearch.ru/articles/cs/postfix-evaluation/index.htm
  Created : 03/09/02 (dd/mm/yy)
  Web : http://www.qiksearch.ru
  E-mail : qiksearch@rediffmail.ru
*/
function push_stack(stackArr,ele)
{
 stackArr[stackArr.length]=ele;
}
function pop_stack(stackArr)
{
 var _temp=stackArr[stackArr.length-1];
 delete stackArr[stackArr.length-1];
 stackArr.length--;
 return(_temp);
}
function isOperand(who)
{
 return(!isOperator(who)? true : false);
}
function isOperator(who)
{
 return((who=="+" || who=="-" || who=="*" || who=="/" || who=="(" || who==")")? true : false);
}
function topStack(stackArr)
{
 return(stackArr[stackArr.length-1]);
}
function PostfixToInfix(postfixStr)
{
 var stackArr=new Array();
 postfixStr=postfixStr.split("");
 for(var i=0; i<postfixStr.length; i++)
 {
  if(isOperand(postfixStr[i]))
  {
   push_stack(stackArr,postfixStr[i]);
  }
  else
  {
   var temp=topStack(stackArr);
   pop_stack(stackArr);
   var pushVal=topStack(stackArr)+postfixStr[i]+temp;
   pop_stack(stackArr);
   push_stack(stackArr,pushVal);
  }
 }
 return(topStack(stackArr));
} 
</script>
<!--END POSTFIX TO INFIX JAVASCRIPT-->
<center><span class="header">Postfix to Infix Conversion</span></center>
<!--BEGIN FORM-->
<center>
<form name="input_form">
<table class="form_in" cellspacing="0" cellpadding="3">
 <tr bgcolor="#0066CC">
  <td><font face="verdana,arial,helvetica" size="-2" color="#FFFFFF">Postfix Expression :</font></td>
  <td><font face="verdana,arial,helvetica" size="-2" color="#FFFFFF">Infix Expression :</font></td>
  <td></td>
 </tr>
 <tr>
  <td><input type="text" name="postfixVal" class="text_box" value=""></td>
  <td><input type="text" name="infixVal" class="text_box" value=""></td>
  <td align="bottom"><input type="button" onClick="document.input_form.infixVal.value=PostfixToInfix(document.input_form.postfixVal.value)" value="Postfix to Infix" class="button"></td>
 </tr>
</table>
</form>
</center>
<!--END FORM-->
<table width="465" align="center"><tr><td>
 <font face="verdana,arial,helvetica" size="-1" color="#000000">
 This is the "JavaScript" Implementation of converting a Postfix(Postorder) expression to Infix(Inorder) expression.
 <br><br>It is a small modification of <a href="http://www.qiksearch.ru/javascripts/postfix-evaluator.htm" class="link">Postfix Evaluator</a>.<br>For the algorithm used in "Postfix Evaluator" <a href="http://www.qiksearch.ru/articles/cs/postfix-evaluation/index.htm" class="link">click here</a>.
 <hr style="color:#003366; height:1px">
 &#169 2002 <a href="http://www.qiksearch.ru" class="link" title="Click here to visit Qiksearch.ru">Premshree Pillai</a>.
 </font>
</td></tr></table>
</body>
</html>
Источник — «http://wbex.ru/index.php?title=JavaScript_DHTML/Development/Postfix_Infix&oldid=1809»