Postfix to Infix
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/*
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.com/javascripts/postfix-evaluator.htm
See algorithm at
-http://www.qiksearch.com/articles/cs/postfix-evaluation/index.htm
Created : 03/09/02 (dd/mm/yy)
Web : http://www.qiksearch.com
E-mail : qiksearch@rediffmail.com
*/
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
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));
}
Postfix to Infix Conversion
Postfix Expression :
Infix Expression :
This is the "JavaScript" Implementation of converting a Postfix(Postorder) expression to Infix(Inorder) expression.
It is a small modification of Postfix Evaluator.
For the algorithm used in "Postfix Evaluator" click here.
© 2002 Premshree Pillai.