iterator for template

[xu@la]

Hi,

I have a template map and want to use the iterator. But the compile
failed. Is there any restriction on the (const) iterator for template
type?

Sample code:

template <typename T>
void Foo(const std::map<std::string, std::vector<T> > &data) {
const std::map<std::string, std::vector<T> >::const_iterator it =
data.begin();
// ...
}


Thanks,
xu@la

 

[Vincent Jacques]

Hi,

xu@la a écrit :

template <typename T>
void Foo(const std::map<std::string, std::vector<T> > &data) {
const std::map<std::string, std::vector<T> >::const_iterator it =
data.begin();
// ...
}

const typename std::map<std::string, std::vector<T> >::const_iterator it
^^^^^^^^

The 'problem' is that you are in a template, trying to invoke a
dependent name (your const_iterator depends on T), so you must help the
compiler, and tell it it is a type.

I hope it helps,

 

[xu@la]

Thanks! It works.

Jinjun

Hi,

xu@la a écrit :


const typename std::map<std::string, std::vector<T> >::const_iterator it
       ^^^^^^^^

The 'problem' is that you are in a template, trying to invoke a
dependent name (your const_iterator depends on T), so you must help the
compiler, and tell it it is a type.

I hope it helps,