Exception in two line Xerces program

Question

The following code gives me an exception on the XMLFormatTarget line, but if I change the string from "C:/test.xml" to "test.xml" it works fine.

// test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <xercesc/util/XMLString.hpp>
#include <xercesc/framework/LocalFileFormatTarget.hpp>

using namespace xercesc;

int main()
{
    XMLPlatformUtils::Initialize();

    XMLFormatTarget *formatTarget = new LocalFileFormatTarget("C:/test.xml"); 

    return 0;
}

[edit] Xerces exception is:

Error Message: unable to open file 'C:\test.xml'

Windows exception is:

Access is denied

Answer 1

It could be that you don't have sufficient permissions to write to C:\. In such a case, Xerces might report the error throwing an exception.

An Access Denied exception is typically what we could expect if you try to write to a system directory without administrator credentials.

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Maybe it has also something to do with the directory separators:

XMLFormatTarget *formatTarget = new LocalFileFormatTarget("C:\\test.xml");

On Windows, directory separators are backslashes "\". Some libraries don't care (and I never used Xerces, so I can't tell). In C and C++, backslash is also an escape character and so you must double it if you want a litteral "\" in your string.

Also, telling us what was the exception you got would help us even more.

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Not directly related, but from your code, it seems you never delete formatTarget. I assume this is sample code, but if it is not, you should add the following line to your code:

delete formatTarget;

Or use a scoped pointer instead:

boost::scoped_ptr<XMLFormatTarget> formatTarget(new LocalFileFormatTarget("C:\\test.xml"));

To avoid memory leaks.

Answer 2

Try transcoding the filename:

// Convert the path into Xerces compatible XMLCh*. 
XMLCh *tempFilePath = XMLString::transcode(filePath.c_str()); 

// Specify the target for the XML output. 
XMLFormatTarget *formatTarget = new LocalFileFormatTarget(tempFilePath);

as per this answer to a similar question.

Answer 3

If you use only test.xml you specify a path relative to the current working directory (usually where the program was started from). So if your program is not directly on your C: drive, the two runs could point to different files. The C:\test.xml could have an error, but C:\Path\to\your\program\test.xml correct, so the latter gives you no exception.

Anyway, as ereOn said, it would help if we knew which exception is thrown.