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Template problem
- To: help-gcc at gnu dot org
- Subject: Template problem
- From: Michael Ben-Gershon <mybg at netvision dot net dot il>
- Date: Tue, 28 Dec 1999 22:34:10 +0200
- Newsgroups: gnu.gcc.help
- Organization: My Office
- Xref: wodc7nx0 gnu.gcc.help:2308
I am having problems with templates on gcc-2.95.2. I am sure
that the code worked on some earlier version of gcc, but I
don't recall exactly which version it was.
I have a Range class defined as:
template <class T, T lower, T upper>
class Range
{
...
};
It has a number of non-member functions defined for the various
operators. In particular, it has the following defined:
template<class T, T lower, T upper>
ostream&
operator<< (ostream& out_stream, const Range<T, lower, upper>& the_value);
In the main program, I have
int main()
{
Range<int, -5, 5> f = -5;
cout << endl;
cout << "Number is: " << f << endl;
...
When compiling (all the code, including the implementation of the
function above, is in one file) I get the following error:
test_range.cc: In function `int main()':
test_range.cc:18: no match for `ostream & << Range<int,-5,5> &'
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:77:
candidates are: class ostream & ostream::operator <<(char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:78:
class ostream & ostream::operator <<(unsigned char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:79:
class ostream & ostream::operator
etc, etc, etc ...
The strange thing is that I have a derived class, which behaves fine!
It is defined as:
template<int lowest, int highest>
class Floor_Number : public Range<int, lowest, highest>
{
...
};
With the ostream stuff defined as:
template<int lowest, int highest>
ostream&
operator<< (ostream& out_stream, const Floor_Number<lowest, highest>&
the_value);
and is used in the test program as:
Floor_Number<-3, 10> Ff = -5;
cout << "The floor is: " << Ff << endl;
What is wrong with the Range stuff? If it is wrong, how is it that the derived
class Floor_Number is OK?
Thanks,
Michael Ben-Gershon
mybg@netvision.net.il