Re: What's wrong with this template definition?
On Dec 22, 10:18 pm, Bertwim <b...@xs4all.nl> wrote:
Hi, I'm struggling with templates.
#include <map>
template <class T>
class symtblpp
{
private:
typedef std::map< std::string, T > maptype;
maptype _map;
public:
T* lookup( const std::string& );};
=====================
In the implemantation file (.cpp) the member function lookup is defined:
=======================
template <typename T>
T* symtblpp<T>::lookup( const std::string& key )
{
maptype::iterator it = _map.find( key );
return &(*it);}
=======================
The compile (g++ 4.3.1) complains:
symtblpp.cpp:42: error: expected `;' before ?it?
symtblpp.cpp:45: error: ?it? was not declared in this scope
where line 42 refers to the line with the iterator.
Can somebody explain to me what's wrong?
Thanks in advance.
Bertwim
{ Short answer: use "typename" in front of maptype::iterator. -mod/sk }
Interesting. The code compiled as is with VC2005 and VC2008.
Under Comeau online compiling http://www.comeaucomputing.com/tryitout/
I had to add the #include <string> to compile it enough to get
the msg
"ComeauTest.c", line 17: error: expected a ";" (perhaps on the
previous statement)
maptype::iterator it = _map.find( key );
Correcting the line to
typename maptype::iterator it = _map.find( key );
obviously fixed the problem.
Obviously the real find checks for end() before derefencing and
returing the
address.
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