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Strings as Arrays
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//------------------STRING-ARRAY UTILITIES-------------------
// Find the substring at index n, counting 0 to n
function doIndex(aString, n)
{
var str=""+aString
// Count until the correct index
for(var i = 0; i < n; i++)
{
var where = str.indexOf(':', 1)
str = str.substring(where+1, str.length)
}
// Lop off the end of the string
return str.substring(0, str.indexOf(':'))
}
// Month string
var months = "January:February:March:April:May:June:July:"+
"August:September:October:November:December:"
function choose()
{
document.forms[0].month.value=
doIndex(months, document.forms[0].input.options.selectedIndex)
}
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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>Treating a String as an Array</H1></FONT>
<FONT COLOR="770000">
Sometimes it is easier to store information in strings
rather than arrays. This saves lines of code and increases
maintainability. This example
shows one way to store month names in a string and index
them.
</FONT></BLOCKQUOTE>
<BR><BR>
</SCRIPT><CENTER><FORM><TABLE BORDER=1>
<TR>
<TD align=center colspan=3><input type="text" name="month" value=""
size=12">Month</TD>
</TR>
<TR>
<TD align=center colspan=3>Number:
<SELECT NAME="input" SIZE="1">
<OPTION>1
<OPTION>2
<OPTION>3
<OPTION>4
<OPTION>5
<OPTION>6
<OPTION>7
<OPTION>8
<OPTION>9
<OPTION>10
<OPTION>11
<OPTION>12
</SELECT><p>
</TD>
</TR>
<TR>
<TD align=center colspan=3>
<input type="button" value="Lookup Indexed Month" onClick="choose()"></TD>
</TR>
</TABLE></FORM></CENTER>
<br><br>
<FONT COLOR="007777"><H2>Discussion</H2></FONT>
<FONT SIZE=4>
Reuse this routine for any data-collection strings. This routine
may be somewhat awkward, but it collapses data information into
a compact, convenient representation and uses a minimum of extra
memory.
</FONT>
<FONT COLOR="770000"><PRE>
// Month string
var months = "January:February:March:April:May:June:July:"+
"August:September:October:November:December:"
// Find the substring at index n, counting 0 to n
function doIndex(aString, n)
{
var str=""+aString
// Count until the correct index
for(var i = 0; i < n; i++)
{
var where = str.indexOf(':', 1)
str = str.substring(where+1, str.length)
}
// Lop off the end of the string
return str.substring(0, str.indexOf(':'))
}
function choose()
{
document.forms[0].month.value=
doIndex(months, document.forms[0].input.options.selectedIndex)
}
</PRE></FONT>
<h5>Copyright ©1996 by Charles River Media, All Rights Reserved</h5>
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