从前端返回给DLL一组string 是XML,如何判断能力是否存在元素如
<?xml version="1.0" encoding="GB2312"?>
<PrintInfoList>
<PrintInfo begin_time="2006-08-02 11:37:12.390" check_id="2" date_valid="2008-08-02 11:37:12.390" dept_id="1" drug_id="1" end_time="2007-08-02 11:37:12.390" from_dept_id="223" input_code="20030202" list_no="20030202" pack_level="2" to_dept_id="3" user_id="223" visit_id="212" ward_id="11" strHosName="第九人民医院" caption="测试文挡" field="1" types="1" count="1" SelectCredit="1" EdtWard_Name="sdfasdfasdf"/>
</PrintInfoList>
中是否存在begin_time的元素