public member function
<unordered_map>
| container iterator (1) |
const_iterator cend() const noexcept;
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| bucket iterator (2) |
const_local_iterator cend ( size_type n ) const; |
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Return const_iterator to end
Returns a const_iterator pointing to the past-the-end element in the unordered_multimap container (1) or in one of its buckets (2).
The const_iterator returned by cend does not point to any element, but to the position that follows the last element in the unordered_multimap container or in one of its buckets (i.e., their past-the-end position). Thus, the value returned shall not be dereferenced - it is generally used to describe the open-end of a range, such as [cbegin,cend).
Notice that an unordered_multimap object makes no guarantees on which order its elements follow. But, in any case, the range that goes from its cbegin to its cend covers all the elements in the container (or the bucket), until invalidated.
A const_iterator is an iterator that points to const content. This iterator can be increased and decreased (unless it is itself also const), just like the iterator returned by unordered_multimap::end, but it cannot be used to modify the contents it points to.
Parameters
- n
- Bucket number. This shall be lower than bucket_count.
It is an optional parameter that changes the behavior of this member function: if set, the const_iterator retrieved points to the past-the-end element of a bucket, otherwise it points to the past-the-end element of the container.
Member type size_type is an unsigned integral type.
Return Value
A const_iterator to the element past the end of the container (2) or the bucket (2).
Both const_iterator and const_local_iterator are member types. In the unordered_multimap class template, these are forward iterator types.
const_local_iterator is an interator of the same category as const_iterator. Their value_type, difference_type, pointer and reference member types are also the same. But the iterators themselves are not necessarily of the same type.
Example
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// unordered_multimap::cbegin/cend example
#include <iostream>
#include <unordered_map>
int main ()
{
std::unordered_multimap<std::string,std::string> myumm = {
{"apple","red"},
{"apple","green"},
{"orange","orange"},
{"strawberry","red"}
};
std::cout << "myumm contains:";
for ( auto it = myumm.cbegin(); it != myumm.cend(); ++it )
std::cout << " " << it->first << ":" << it->second; // cannot modify *it
std::cout << std::endl;
std::cout << "myumm's buckets contain:\n";
for ( unsigned i = 0; i < myumm.bucket_count(); ++i) {
std::cout << "bucket #" << i << " contains:";
for ( auto local_it = myumm.cbegin(i); local_it!= myumm.cend(i); ++local_it )
std::cout << " " << local_it->first << ":" << local_it->second;
std::cout << std::endl;
}
return 0;
}
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Possible output:
myumm contains: apple:red apple:green orange:orange strawberry:red
myumm's buckets contain:
bucket #0 contains:
bucket #1 contains:
bucket #2 contains: apple:red apple:green
bucket #3 contains: orange:orange
bucket #4 contains: strawberry:red
|
Iterator validity
No changes.