C ++ STL，常量迭代器，find（）

Question

I'm currently learning STL and I got some uncertainities about find and const iterators. Let's say I have a find function:

some_stl_container::const_iterator found = myContainer.find(value);

After that should I check what I got for found against another const_iterator, or is it valid to make a check against simply an iterator. Basically would there be any difference between doing this:

if(found!=myContainer.cend())

and this:

if(found!=myContainer.end())

The first looks more accurate(at least to me), but the second should work fine too, right?

Answer 1

All standard library containers satisfy the requirement that Container::iterator is convertible to Container::const_iterator . So both comparisons are valid and will yield the same result.

From §23.2.1 - Table 96

X::iterator ... any iterator category that meets the forward iterator requirements. convertible to X::const_iterator .

Answer 2

Checking if your iterator is different from myContainer.end() is fine. cend and cbegin methods are only here to explicitely obtain const iterators, so that makes no difference in your case.

Note that you could do auto found = myContainer.find(value) in c++11 to infer the iterator type, and that some people will argue that Standard library is the correct name (not STL).