Entry
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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