小编use*_*727的帖子

<LIST_R7P1_1>
 <R7P1_1> 
 <ORIG_EXP_PRE_CONV /> 
  <EXP_AFT_CONV >34<EXP_AFT_CONV />
  <GUARANTEE_AMOUNT /> 
  <CREDIT_DER /> 
 </R7P1_1>
</LIST_R7P1_1>


<total><xsl:value-of select="LIST_R7P1_1/R7P1_1/ORIG_EXP_PRE_CONV + LIST_R7P1_1/R7P1_1/EXP_AFT_CONV + LIST_R7P1_1/R7P1_1/GUARANTEE_AMOUNT + LIST_R7P1_1/R7P1_1/CREDIT_DER"/></total>

总的来说,由于像<CREDIT_DER />, <ORIG_EXP_PRE_CONV /> 等等空元素,我得到空值.

如何处理,以便我可以获得数值

请建议