undefined reference to

[taniaj]

hi, i'm new on Linux and i have some problems compiling my program.
iḿ trying to parse a file using html parser by libxml.

#include <stdio.h>
#include <libxml/HTMLparser.h>
#include <string.h>

void main(){
	printf("main\n");
	
	htmlDocPtr doc;
	void* pd;
	char *filename;
	
	xmlSAXHandler handler = {
		NULL, /* internalSubset */
		NULL, /* isStandalone */
		NULL, /* hasInternalSubset */
		NULL, /* hasExternalSubset */
		NULL, /* resolveEntity */
		NULL, /* getEntity */
		NULL, /* entityDecl */
		NULL, /* notationDecl */
		NULL, /* attributeDecl */
		NULL, /* elementDecl */
		NULL, /* unparsedEntityDecl */
		NULL, /* setDocumentLocator */
		NULL, /* startDocument */
		NULL, /* endDocument */
		NULL, /* startElement */
		NULL, /* endElement */
		NULL, /* reference */
		NULL, /* characters */
		NULL, /* ignorableWhitespace */
		NULL, /* processingInstruction */
		NULL, /* comment */
		NULL, /* xmlParserWarning */
		NULL, /* xmlParserError */
		NULL, /* xmlParserError */
		NULL, /* getParameterEntity */
		NULL, /* cdataBlock */
		NULL, /* externalSubset */
		1,    /* initialized */
		NULL, /* private */
		NULL, /* startElementNsSAX2Func */
		NULL, /* endElementNsSAX2Func */
		NULL  /* xmlStructuredErrorFunc */
	};
	
	doc=htmlSAXParseFile(NULL,NULL,NULL,NULL);


	return;

}

when i compile (gcc -o html -I/usr/include/libxml2 tracker-extract-xml.c) i receive this message:

/tmp/ccCZWbiT.o: In function `main':
tracker-extract-xml.c.text+0x4c): undefined reference to `htmlSAXParseFile'
collect2: ld returned 1 exit status

how can i solve this problem?
thanks in advance for your help.

[hazel]

You may have given the wrong path for your HTMLparser.h. Most systems nowadays use libxml2. Try using libxml2/libxml.

It's always a good idea when using a library for the first time to check up where it actually lives and where the header files are.

[taniaj]

thanks for your answer.

but unfortunately it still doesn't work

if i replace #include <libxml/HTMLparser.h> with #include <libxml2/libxml/HTMLparser.h> the compiler gives me the following message (and other similar ones):

/usr/local/include/libxml2/libxml/HTMLparser.h:15:31: error: libxml/xmlversion.h: No such file or directory

there's a problem with the position of file.h, but i have no idea how to deal with them.
the folder libxml2 is in /usr/include and in /usr/local/include. in both the libxml2 folders there's the folder libxml containing both HTMLparser.h and xmlversion.h. in HTMLparser.h all the include are like #include <libxml/file.h>

[Cabhan]

This is an ld error, not a gcc error. The error is because in your compiled program, the function htmlSAXParseFile cannot be found.

The reason is because you are not linking against the correct libraries. I've never used libxml, but the library is probably called libxml.so, so add this flag to your gcc command:

-lxml

[taniaj]

thank you very much..with the option -lxml2 it works