In XSLT, how do I use a for-each loop? - xslt

Question

If I had a bunch of fields on a screen, say ten for first name and ten for last name, and they're named firstName1, firstName2, etc., and lastName1, lastName2, etc., how would I create a loop that goes through each last name field?
Right now, I have it set up to perform a task ten times, one for each last name field. How can I set up a for-each loop that goes through lastName1, lastName2, lastName3...lastName10 and does a specific task for each of them?
Input XML:
<Arguments>
<EnteredBy>SDSADFSADF</EnteredBy>
<IDNumber>WERWEW</IDNumber>
<Book1>Y</Book1>
<LastName1>ASDFASFASDFASFA</LastName1>
</Arguments>
XSLT:
<xsl:apply-templates select="/myQuery/Arguments/lastName1"/>
and there are lastName2 through lastName10, as well.
I want to loop through each of the ten and truncate the last names to five characters.

Answer 1

The simplest and most idiomatic form of iteration in XSLT is to use xsl:apply-templates on the set of elements you want to handle. If you don't see how to use that idiom to solve your problem, it's worth spending time working to learn it.
[Addendum:]
For example:
<xsl:template match="/myQuery/Arguments">
...
<xsl:element name="Arguments">
<xsl:apply-templates/>
</
...
</
<xsl:template match="lastName1 | lastName2 | lastName3
| ... | lastName9">
<xsl:element name="{name()">
<xsl:value-of select="substring(.,1,5)"/>
</
</
This assumes you have elements names lastName1, lastName2, etc., instead of the simpler idiom where all last names are called (wait for it!) lastName, and that what you want in this particular part of the document is a near-identity transform.
XSLT does also have an xsl:for-each, which can be regarded as syntactic sugar for xsl:apply-templates and is sometimes preferred by programmers with a procedural bent. If you think of it as analogous to a loop in an imperative language, however, your instincts will eventually fail you and you will be surprised because your attempts at variable mutation don't work the way you expected them to.
Systematic work through a good book or tutorial will pay off.

Answer 2

Here's what I got to work:
<xsl:template match="/">
<xsl:element name="Arguments">
<xsl:apply-templates />
</xsl:element>
</xsl:template>
<xsl:template match="Arguments">
<xsl:for-each select="./*[contains(name(), 'LastName')]">
<xsl:call-template name="test">
</xsl:call-template>
</xsl:for-each>
</xsl:template>
<xsl:template name="test">
<xsl:element name="{name()}">
<xsl:value-of select="."/>
</xsl:element>
</xsl:template>
This way you don't need to make 9 calls, just one per loop.
Or if you want to avoid the for-each, you can do this instead:
<xsl:template match="Arguments/*[contains(name(), 'LastName')]">
<xsl:element name="{name()}">
<xsl:value-of select="."/>
</xsl:element>
</xsl:template>