Question

I have an xsl:variable that can be either the empty string or a number. So I evaluate it like this:

<xsl:if test="number($var)"><node att="{number($var)}" /></xsl:if>

This works if var is the empty string, but it has the same effect if var is 0:

From -2 to 2:

<node att="-2" />
<node att="-1" />
<node att="1" />
<node att="2" />

Is this a bug? Is there a different version of the number function that also captures 0? Do I really have to add or $var = '0' to my test statement?

Answer 1

It is taken from XPath test if node value is number
Test the value against NaN:

<xsl:if test="string(number(myNode)) != 'NaN'">
    <!-- myNode is a number -->
</xsl:if>

This is a shorter version:

<xsl:if test="number(myNode) = myNode">
    <!-- myNode is a number -->
</xsl:if>

<xsl:if test="number(0)">

the expression number(0) is evaluated to the boolean false() — because by definition

boolean(0) is false()