Question

When I try to compile template class, I got the following errors:

C.cpp: In member function 'void PeriodContainerAdvanced<T>::add()':
C.cpp:133: error: type/value mismatch at argument 1 in template parameter list for 'template<class _T1, class _T2> struct std::pair'
C.cpp:133: error:   expected a type, got 'std::map<int,T,std::less<int>,std::allocator<std::pair<const int, T> > >::iterator'
C.cpp:133: error: invalid type in declaration before ';' token

Class at C.h file: (Simplified)

template <class T>
class PeriodContainerAdvanced 
{
[skip]
    void add (); 
[skip]
}

C.cpp (Simplified):

template <class T>
void PeriodContainerAdvanced<T>::add()
{
[skip]
    std::pair<std::map< time_t, T >::iterator, bool> ret; // line 133 !
[skip]
}

And the similar error at other function when trying to define

std::map< time_t, T >::iterator it, it_start, it_end; // line 153

after this line compiler say:

C.cpp:153: error: expected `;' before 'it'
C.cpp:166: error: 'it_start' was not declared in this scope

How to fix it? thanks

Answer 1

That’s a dependent name, you’ll need to declare it as:

std::pair<typename std::map< time_t, T >::iterator, bool> ret;

Also, to avoid later linker errors, you should move template implementations to a file visible to all translation units that use that template – like the header where you define your template class.