Converting Traditional Logic to XSLT - regex

Question

Just trying to convert the below simple code into XSLT and I tried to use Regular expressions with XSLT 2.0 but some how it is not working. Could any one please advice? Thank you.
string[256] Fname;
integer ctr;
Fname="";
ctr=0;
while ctr <= len(#FirstName) do
begin
if mid(#FirstName,ctr,1) = "A" |
mid(#FirstName,ctr,1) = "B" |
mid(#FirstName,ctr,1) = "C" |
mid(#FirstName,ctr,1) = "D" |
mid(#FirstName,ctr,1) = "E" |
mid(#FirstName,ctr,1) = "F" |
mid(#FirstName,ctr,1) = "G" |
mid(#FirstName,ctr,1) = "H" |
mid(#FirstName,ctr,1) = "I" |
mid(#FirstName,ctr,1) = "J" |
mid(#FirstName,ctr,1) = "K" |
mid(#FirstName,ctr,1) = "L" |
mid(#FirstName,ctr,1) = "M" |
mid(#FirstName,ctr,1) = "N" |
mid(#FirstName,ctr,1) = "O" |
mid(#FirstName,ctr,1) = "P" |
mid(#FirstName,ctr,1) = "Q" |
mid(#FirstName,ctr,1) = "R" |
mid(#FirstName,ctr,1) = "S" |
mid(#FirstName,ctr,1) = "T" |
mid(#FirstName,ctr,1) = "U" |
mid(#FirstName,ctr,1) = "V" |
mid(#FirstName,ctr,1) = "W" |
mid(#FirstName,ctr,1) = "X" |
mid(#FirstName,ctr,1) = "Y" |
mid(#FirstName,ctr,1) = "Z" |
mid(#FirstName,ctr,1) = "a" |
mid(#FirstName,ctr,1) = "b" |
mid(#FirstName,ctr,1) = "c" |
mid(#FirstName,ctr,1) = "d" |
mid(#FirstName,ctr,1) = "e" |
mid(#FirstName,ctr,1) = "f" |
mid(#FirstName,ctr,1) = "g" |
mid(#FirstName,ctr,1) = "h" |
mid(#FirstName,ctr,1) = "i" |
mid(#FirstName,ctr,1) = "j" |
mid(#FirstName,ctr,1) = "k" |
mid(#FirstName,ctr,1) = "l" |
mid(#FirstName,ctr,1) = "m" |
mid(#FirstName,ctr,1) = "n" |
mid(#FirstName,ctr,1) = "o" |
mid(#FirstName,ctr,1) = "p" |
mid(#FirstName,ctr,1) = "q" |
mid(#FirstName,ctr,1) = "r" |
mid(#FirstName,ctr,1) = "s" |
mid(#FirstName,ctr,1) = "t" |
mid(#FirstName,ctr,1) = "u" |
mid(#FirstName,ctr,1) = "v" |
mid(#FirstName,ctr,1) = "w" |
mid(#FirstName,ctr,1) = "x" |
mid(#FirstName,ctr,1) = "y" |
mid(#FirstName,ctr,1) = "z" |
mid(#FirstName,ctr,1) = "-"
then
Fname = Fname + mid(#FirstName,ctr,1);
ctr = ctr+1;
end
Fname = trimleft(Fname,"-");
if len(Fname) = 2 then
Fname = Fname + "-";
if len(Fname) = 1 then
Fname = Fname + "--";
if len(Fname) > 50 then
Fname = left(Fname,50);
if len(Fname) = 0 then
Fname = "UNKNOWN";
#FirstName = Fname;
Solution:
Same logic is applied on another filed called PostalCode and here is what I tried but some how regular expression not working. I am trying to fix it mean while posting here as well for experts solutions.
<xsl:if test="contains(substring(string(/OrdersToFulfill/Order/OrderHeader/BillTo/Address/PostalCode),1,1),'[^a-zA-Z1-9. ]')">
<xsl:variable name="vPostalCode"
select="concat(string(/OrdersToFulfill/Order/OrderHeader/BillTo/Address/PostalCode),substring(string(/OrdersToFulfill/Order/OrderHeader/BillTo/Address/PostalCode),1,1))"/>
<xsl:element name="PostalCode">
<xsl:if test="string-length($vPostalCode) < 9 ">
<xsl:value-of
select="substring($vPostalCode,1, 5)"/>
</xsl:if>
<xsl:if test="string-length(string(/OrdersToFulfill/Order/OrderHeader/BillTo/Address/PostalCode)) > 10 ">
<xsl:value-of
select="substring($vPostalCode,1, 10)"/>
</xsl:if>
</xsl:element>
</xsl:if>

Answer 1

OK, I think I've worked out what your code does: it constructs a string containing all the letters, digits, and hyphens from an input string, and removes everything else. It then pads with hyphens to a minimum length of three, and truncates to a maximum length of 50. (Why couldn't you have told us that?)
Also, if you tried to write the code and it didn't work then you should show us the code so we can tell you where you went wrong.
The first part of the problem can be done using
replace($in, "[^A-Za-z0-9\-]", "")
Padding with hyphens to length 3 can be done with
if (string-length($s) lt 3)
then substring(concat($s, "---"), 1, 3)
else $s
Truncation to a maximum of 50 characters can be done with
substring($s, 1, 50)