Regex replace help

[Richard Shaw]

I'm writing my own cmake module for finding TinyXML and I'm trying to
extract the version from the header.

For some reason it's matching the whole file no matter what I do. I've
looked through several of the cmake modules in
/usr/share/cmake/Modules and don't see what I'm doing that's so
different.

The relevant lines in /usr/include/tinyxml.h are:

const int TIXML_MAJOR_VERSION = 2;
const int TIXML_MINOR_VERSION = 6;
const int TIXML_PATCH_VERSION = 1;

To speed up the testing I'm trying to come up with a sed equivalent to
make sure it's returning the version numbers properly.

Here's what I have:
$ echo "const int TIXML_MAJOR_VERSION = 2;" | sed 's/const int
TIXML_MAJOR_VERSION = \([0-9]+\).*/\1/'
const int TIXML_MAJOR_VERSION = 2;

The "echo" is one of the lines I'm trying to match while only
returning the version number. For some reason I'm getting the whole
line back...

Can anyone give me a hint before I pull all my hair out?

Thanks,
Richard