CODEWITHSUNDEEP
c++type-conversionlibxml2
Michele
Michele

Reputation: 3871

how convert string to xmlChar

I'm trying to convert a string to an xmlChar. The compiler says no suitable conversion function from const string to xmlChar exists. This is what the code looks like:

bool ClassName::openFile(const String& ZipFile)
{
    //convert 
    const xmlChar *temp = (const xmlChar)ZipFile; //ZipFile has an error here. ZipFile is path and filename
    ...
}

Any ideas? I googled it and people were converting from xmlChar to string but not this direction.

Upvotes: 2

Views: 5082

Answers (3)

Devin
Devin

Reputation: 41

This xml library was written for standard C. There are c style casting methods used at the time that took advantage of the BAD_CAST keyword in the library. Example:

rc = xmlTextWriterWriteElement(writer, BAD_CAST "Value1", BAD_CAST "DATA1");
if (rc < 0) {
    throw EXCEPTION("Error in xmlTextWriterWriteElement");
}

But with c++ if you want to avoid the c-style cast the best you can do is:

rc = xmlTextWriterWriteElement(writer, const_cast<xmlChar*>(reinterpret_cast<const xmlChar *>("Value1")), const_cast<xmlChar*>(reinterpret_cast<const xmlChar *>("DATA1")));

Note that the usual dangers of this casting aren't a problem due to the use case here. We can safely assume the underlying library isn't going to do anything nasty to us.

Upvotes: 0

Rajesh Negi
Rajesh Negi

Reputation: 103

unsafe but removed overhead.

xmlChar *temp = reinterpret_cast<xmlChar*>(ZipFile);

but you must be aware of usage of reinterpret_cast

Upvotes: 0

Darien Pardinas
Darien Pardinas

Reputation: 6186

xmlChar is just a typedef of unsigned char. Just make your sentence like this:

const xmlChar *temp = ZipFile.c_str();

Upvotes: 3

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