[英]Get values from XML <tag> in C++ using libxml2
I am having a hard time to get the values from a XML file. 我很难从XML文件中获取值。 We are using libxml2 and python (output to *.txt) and then C++ to read the *.txt file.
我们使用libxml2和python(输出到* .txt),然后使用C ++读取* .txt文件。
I would like to use libxml2 in C++ without going through Python. 我想在C ++中使用libxml2,而无需通过Python。 My problem is the reader (see example below).
我的问题是读者(请参见下面的示例)。 BTW: I do not get much from this example code from http://xmlsoft.org/examples/index.html#reader1.c
顺便说一句:我从http://xmlsoft.org/examples/index.html#reader1.c的示例代码中得到的并不多
Could someone tell me how i get the value = xmlTextReaderConstValue(reader);
有人可以告诉我如何获取
value = xmlTextReaderConstValue(reader);
into a string? 成串?
In summary: Loop through XMLdoc {if "XML-tag-" == 'tag' then store value/content of "XML-tag-" in mystring} 总结:遍历XMLdoc {如果“ XML-tag-” =='tag'然后在mystring中存储“ XML-tag-”的值/内容}
M 中号
/**
* section: xmlReader
* synopsis: Parse an XML file with an xmlReader
* purpose: Demonstrate the use of xmlReaderForFile() to parse an XML file
* and dump the informations about the nodes found in the process.
* (Note that the XMLReader functions require libxml2 version later
* than 2.6.)
* usage: reader1 <filename>
* test: reader1 test2.xml > reader1.tmp && diff reader1.tmp $(srcdir)/reader1.res
* author: Daniel Veillard
* copy: see Copyright for the status of this software.
*/
#include <stdio.h>
#include <libxml/xmlreader.h>
#ifdef LIBXML_READER_ENABLED
/**
* processNode:
* @reader: the xmlReader
*
* Dump information about the current node
*/
static void
processNode(xmlTextReaderPtr reader) {
const xmlChar *name, *value;
name = xmlTextReaderConstName(reader);
if (name == NULL)
name = BAD_CAST "--";
value = xmlTextReaderConstValue(reader);
printf("%d %d %s %d %d",
xmlTextReaderDepth(reader),
xmlTextReaderNodeType(reader),
name,
xmlTextReaderIsEmptyElement(reader),
xmlTextReaderHasValue(reader));
if (value == NULL)
printf("\n");
else {
if (xmlStrlen(value) > 40)
printf(" %.40s...\n", value);
else
printf(" %s\n", value);
}
}
/**
* streamFile:
* @filename: the file name to parse
*
* Parse and print information about an XML file.
*/
static void
streamFile(const char *filename) {
xmlTextReaderPtr reader;
int ret;
reader = xmlReaderForFile(filename, NULL, 0);
if (reader != NULL) {
ret = xmlTextReaderRead(reader);
while (ret == 1) {
processNode(reader);
ret = xmlTextReaderRead(reader);
}
xmlFreeTextReader(reader);
if (ret != 0) {
fprintf(stderr, "%s : failed to parse\n", filename);
}
} else {
fprintf(stderr, "Unable to open %s\n", filename);
}
}
int main(int argc, char **argv) {
if (argc != 2)
return(1);
/*
* this initialize the library and check potential ABI mismatches
* between the version it was compiled for and the actual shared
* library used.
*/
LIBXML_TEST_VERSION
streamFile(argv[1]);
/*
* Cleanup function for the XML library.
*/
xmlCleanupParser();
/*
* this is to debug memory for regression tests
*/
xmlMemoryDump();
return(0);
}
#else
int main(void) {
fprintf(stderr, "XInclude support not compiled in\n");
exit(1);
}
#endif
I've been using this cast to get the std::string out of the const xmlChar* : 我一直在使用此强制转换来从const xmlChar *中获取std :: string:
my_std_string.assign(reinterpret_cast<const char*>(my_const_xmlchar_ptr));
Don't know if it's the best way but worked well. 不知道这是否是最好的方法,但是效果很好。
I think that what you name the "XML-tag-" is actualy the return of xmlTextReaderConstName(reader)
, name
, wich is a const xmlChar*. 我认为您所说的“ XML-tag-”实际上是
xmlTextReaderConstName(reader)
的返回值, name
,它是一个const xmlChar *。 (See libxml2 xmlreader) (请参阅libxml2 xmlreader)
I suggest the use of string::compare to test the string equality with your "-tag-". 我建议使用string :: compare与您的“ -tag-”测试字符串是否相等。
If strings match, you can then get the value
, a const xmlChar* again, with the xmlTextReaderConstValue(reader);
如果字符串匹配,则可以使用
xmlTextReaderConstValue(reader);
再次获取value
const xmlChar * xmlTextReaderConstValue(reader);
function, cast into a string with the same fashion way, then store it. 函数,以相同的方式转换为字符串,然后将其存储。
value
is a C null-terminated (and statically allocated) string already. value
已经是一个以C空终止(并且静态分配)的字符串。
If you want to get std::string
, you can use something like: 如果要获取
std::string
,可以使用类似以下内容的代码:
std::string val = value;
If you want a C null-terminated string which will be owned by you: 如果要由您拥有的以C终止的C字符串:
xmlChar* val = xmlStrdup(value);
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