XSL - how to set variable as integer if it comes from string

Question

XPTY0004 : The operator ' + ' is not defined for operands of type xs:string and xs:integer

IMPUT:

<?xml version="1.0" encoding="UTF-8"?>
<LeveL Plan="1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema">


<space2000>
<values>
<value jak="77" rak="12"</value>
<value jak="66" rak="345"></value>
<value jak="-50" rak="67"></value>
<value jak="-30" rak="-89">1</value>
</values> 

</space2000>


</LeveL>

MY TRY:

<xsl:stylesheet version="2.0" 
xmlns:fn ="http://www.w3.org/2005/xpath-functions"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<xsl:template match="/">
<xsl:for-each select="(LeveL/space2000/values)">
<xsl:variable name="JJJ"  select="(format-number(((value/@jak) div 2),'0'))"/>
<xsl:variable name="RRR"  select="format-number(((value/@rak) div 2),'0')"/>
<xsl:text>
O
</xsl:text>
<xsl:text>LA</xsl:text>
<xsl:value-of select="$JJJ"></xsl:value-of>
<xsl:text> </xsl:text><xsl:text>LO</xsl:text>
<xsl:value-of select="$RRR"></xsl:value-of>
<xsl:text>
O
</xsl:text>

<xsl:choose>
     <xsl:when test="( $JJJ > '0')">
        <xsl:value-of select="A"/>
     </xsl:when>
     <xsl:when test="( $JJJ < '0')">
        <xsl:value-of select="B"/>
     </xsl:when>
       <xsl:when test="( $RRR > '0')">
        <xsl:value-of select="C"/>
     </xsl:when>
     <xsl:when test="( $RRR < '0')">
        <xsl:value-of select="D"/>
     </xsl:when>   
     <xsl:when test="( ( $RRR + '50') < '0' )">
        <xsl:value-of select="X"/>
     </xsl:when>
     <xsl:when test="( '-100' < ( $RRR + '1') < '100' )">
        <xsl:value-of select="X"/>
     </xsl:when>


</xsl:choose>

</xsl:for-each>

</xsl:template>

</xsl:stylesheet>

so I would like ro recive something like: A C B D X

but xsl

dont't like + ( is not trusting its integer :)

don"t like < ( the other way > is for him acceptable :)

SO MY QUESTION IS

a) How to set variable (or element) as integer able to do mathematics?

b) How to test if variable is bigger than -100 and smaller than 100 ?

PLEASE HEEEEEELP :)

Solution

First, a pure XML issue, nothing to do with XSLT: "<" must be escaped as "<". (But with XSLT 2.0, it's often more convenient to use the "lt" operator rather than "<").

Second point: don't put your numbers in quotes. Write 50, not '50'.

Third: it's a good idea to declare the types of your variables, that way it's much clearer what's going on. e.g.

<xsl:variable name="JJJ" select="format-number(...)" as="xs:string"/>

Finally, if you want to add a string and a number, convert the string to a number first using xs:integer(), xs:double(), or the number() function.