How to declare an iterator for unknown STL container? for example, I want to write a function that recieve container and print it all using iterators:
template <class Container> void print(Container c) {
// how to declare iterator???????
my_iterator = c.begin();
while(my_iterator!=c.end()) {
cout << *my_iterator << endl;
my_iterator++;
}
}
In C++03, you would need to get the iterator type from the container type explicitly:
typename Container::iterator it;
typename Container::const_iterator cit;
In C++11, you can just use auto:
auto my_iterator = c.begin(); // iterator in this case
auto my_iterator = c.cbegin(); // const_iterator always
Also note, as suggested my @Matthieu, that you can use a range based for loop in C++11, to simplify the code:
template <class Container>
void print(const Container& c)
{
for (const auto& elem : c)
cout << c << endl;
}
for (auto const& element: c)
Go for:
for (auto& var : container)
{
cout << var << endl;
}
To display each elements of your container (and of any other type of container, even string or vector or map , ...)
auto it = c.begin();constreference, to avoid making an unnecessary copy.