<HTML><HEAD>
<!--
--------------------------
Strings to Arrays and Back
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<SCRIPT LANGUAGE="JavaScript"><!-- hide from old browsers
/*
THE JAVASCRIPT COOKBOOK by Erica Sadun, webrx@mindspring.com
Copyright (c)2000 by Charles River Media. All Rights Reserved.
This applet can only be re-used or modifed by license holders of the
JavaScript Cookbook CD-ROM. Credit must be given in the source
code and this copyright notice must be maintained. If you do
not hold a license to the JavaScript Cookbook, you may NOT
duplicate or modify this code for your own use.
Use at your own risk. No warranty is given or implied of the suitability
of this applet for any specific application. Neither Erica Sadun nor
Charles River Media will be held responsible for any unwanted effects
due to the use of this applet or any derivative.
*/
// Create an Array
function createArray(n)
{
for (var i = 0; i < n; i++)
this[i] = 0;
return this;
}
// String to Array
function stringArray(aString)
{
var t = new Array();
var s = ""+aString
if (s == ""){
return t;
}
var i = 0
var idx = 0
// search for the colon to create each array item
while ((idx = s.indexOf(':')) != -1)
{
t[i] = s.substring(0, idx)
s = s.substring(idx+1,s.length)
i++
}
// create final array item
t[i]=s;
return t;
}
// Array to String
function arrayString(anArray, len)
{
var s = ""
for (var i = 0; i < (len - 1); i++) s += anArray[i]+":"
if (len > 0) s += anArray[len - 1]
return s
}
// Initialize Global Variables
var myArray = new createArray(50) // 50 should be big enough
var arrayTop = 0; // Top of myArray
// Show the Array
function showArray()
{
document.forms[0].myArray.value = arrayString(myArray, arrayTop)
// prepare for next entry
document.forms[0].input.focus()
document.forms[0].input.select()
}
// Add value to array
function add()
{
myArray[arrayTop]=""+document.forms[0].input.value
arrayTop++; // increase top
showArray()
}
// Clear the array
function clearArray()
{
arrayTop = 0;
document.forms[0].input.value=''
document.forms[0].myArray.value=''
for(var i = 0; i < myArray.length; i++)
myArray[i] = '';
showArray()
}
// Enter a string
function enter()
{
var s = ""+document.forms[0].myArray.value;
var ra = stringArray(s);
arrayTop = ra.length;
for (var i = 0; i < arrayTop; i++) myArray[i] = ra[i];
showArray();
return true;
}
// Sort the array using a simple bubblesort
function sort()
{
for (var i = 0; i < arrayTop; i++)
{
for (var j = i; j < arrayTop; j++)
if (myArray[i] > myArray[j])
{
// out of order: swap them.
var tmp = myArray[i]
myArray[i] = myArray[j]
myArray[j] = tmp
}
}
showArray()
}
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<BODY bgcolor="ffffff" link="0000ff" vlink="770077"
onLoad="document.forms[0].input.focus();document.forms[0].input.select()">
<FONT COLOR="007777"><H1><IMG SRC="../GRAFX/UTENS.JPG" WIDTH=80 HEIGHT=50
ALIGN = CENTER>Strings to Arrays and Back</H1></FONT>
<FONT COLOR="770000">
This applet demonstrates how array data may be stored to
and recovered from strings. For example: <ul>
<li>Type 'f' and tap [Add to Array];
<li>Type 'a' and tap [Add to Array];
<li>Tap on the top text entry field to change focus;
<li>Add in ':c:d:g:e:b';
<li>Tap [Sort Array].
</ul>
</FONT></BLOCKQUOTE>
<BR><BR>
</SCRIPT><CENTER><FORM><TABLE BORDER=1>
<TR>
<TD align=center colspan=3><input type="text" name="myArray" value=""
size=40 onBlur="enter()">String</TD>
</TR>
<TR>
<TD align=center colspan=3><input type="text" name="input"
value="" size=8></TD>
</TR>
<TR>
<TD align=center>
<input type="button" value="Sort Array" onClick="sort()"></TD>
<TD align=center>
<input type="button" value="Add to Array" onClick="add()"></TD>
<TD align=center>
<input type="button" value="Clear Array" onClick="clearArray()"></TD>
</TR>
</TABLE></FORM></CENTER>
<br><br>
<FONT COLOR="007777"><H2>Discussion</H2></FONT>
<FONT SIZE=4>
Tapping on [Add to Array] directly adds data to the array data
structure. This structure is converted to a string and shown
in the text box labeled "String". This field, too, may
be edited. When it senses a field "blur" event, it transforms
its string into an array. This array can be sorted, transformed
back to a string, and displayed.<p>
This method of converting arrays to strings and back will be
particularly useful to PERL programmers.
</FONT>
<FONT COLOR="770000"><PRE>
// String to Array
function stringArray(aString)
{
var i = 0
var idx = 0
var s = ""+aString
if (s == "")
{
// this.length = 0
return this
}
// search for the colon to create each array item
while ((idx = s.indexOf(':')) != -1)
{
this[i] = s.substring(0, idx)
s = s.substring(idx+1,s.length)
i++
}
// create final array item
this[i]=s
// this.length = i+1
return this
}
// Array to String
function arrayString(anArray, len)
{
var s = ""
for (var i = 0; i < (len - 1); i++) s += anArray[i]+":"
if (len > 0) s += anArray[len - 1]
return s
}
</PRE></FONT>
<h5>Copyright ©2000 by Charles River Media, All Rights Reserved</h5>
</BODY>
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