Expat XML parser in c++ application

[bmsce engg]

Hi,
Our c++ application makes use of expat parser to parse an XML file. If there is a long string to be read as tag value like below:

<tag>why does expat read this string in parts</tag>

So, we have "characterValue" method registered to be called when expat encounters value. When I print the characters read by expat in this method, it does not show the entire string, but shows parts of it in subsequent calls to this registered method.
Part 1: why does exp
Part 2: at read this string
Part 3: in parts

So, we had to handle this by appending the parts in subsequent calls to characterValue until end tag is reached, and thats how we got hold of entire string. So, instead of reading it in one shot and making only one call to "characterValue" method, it sometimes makes three calls ( could take less or more ).

Here are my queries:
1) What is the criteria for this selective reading?
2) Is there a way to tell expat to read entire value in one shot?

Please note that we have enough buffer to hold the entire string.

Any help would be highly appreciated.

Thanks.