Multimap Flashcards
Iterators
begin
cbegin( )
returns an iterator to the beginning
Parameters
(none)
Return value
Iterator to the first element.
Complexity
Constant.
Iterators
end
cend( )
returns an iterator to the end
Parameters
(none)
Return value
Iterator to the element following the last element.
Complexity
Constant.
Iterators
rbegin
crbegin( )
returns a reverse iterator to the beginning
Parameters
(none)
Return value
Reverse iterator to the first element.
Complexity
Constant.
Iterators
rend
crend( )
returns a reverse iterator to the end
Parameters
(none)
Return value
Reverse iterator to the element following the last element.
Complexity
Constant.
Capacity
empty( )
checks whether the container is empty
Parameters
(none)
Return value
true if the container is empty, false otherwise
Complexity
Constant.
Capacity
size( )
returns the number of elements
Parameters
(none)
Return value
The number of elements in the container.
Complexity
Constant.
Capacity
max_size( )
returns the maximum possible number of elements
Parameters
(none)
Return value
Maximum number of elements.
Complexity
Constant.
Modifiers
clear( )
clears the contents
Parameters
(none)
Return value (none)
Complexity
Linear in the size of the container, i.e., the number of elements.
Modifiers
insert( )
inserts elements or nodes
Parameters
hint -
iterator, used as a suggestion as to where to start the search (until C++11)
iterator to the position before which the new element will be inserted (since C++11)
value - element value to insert
first, last - range of elements to insert
ilist - initializer list to insert the values from
nh - a compatible node handle
Type requirements
-InputIt must meet the requirements of LegacyInputIterator.
Return value
1-4) Returns an iterator to the inserted element.
5-6) (none)
7,8) End iterator if nh was empty, iterator pointing to the inserted element otherwise.
Exceptions
1-4) If an exception is thrown by any operation, the insertion has no effect.
This section is incomplete
Reason: cases 5-6
Complexity
1-2) Logarithmic in the size of the container, O(log(size())).
3-4) Amortized constant if the insertion happens in the position just after the hint, logarithmic in the size of the container otherwise.
(until C++11)
3-4) Amortized constant if the insertion happens in the position just before the hint, logarithmic in the size of the container otherwise.
(since C++11)
5-6) O(N*log(size() + N)), where N is the number of elements to insert.
7) Logarithmic in the size of the container, O(log(size())).
8) Amortized constant if the insertion happens in the position just before the hint, logarithmic in the size of the container otherwise.
Modifiers
emplace( )
constructs element in-place
Parameters
args - arguments to forward to the constructor of the element
Return value
Returns an iterator to the inserted element.
Exceptions
If an exception is thrown by any operation, this function has no effect.
Complexity
Logarithmic in the size of the container.
Modifiers emplace_hint( )
constructs elements in-place using a hint
Parameters
hint - iterator to the position before which the new element will be inserted
args - arguments to forward to the constructor of the element
Return value
Returns an iterator to the newly inserted element.
Exceptions
If an exception is thrown by any operation, this function has no effect (strong exception guarantee).
Complexity
Logarithmic in the size of the container in general, but amortized constant if the new element is inserted just before hint.
Modifiers
erase( )
erases elements
Parameters
pos - iterator to the element to remove
first, last - range of elements to remove
key - key value of the elements to remove
Return value
1-2) Iterator following the last removed element.
3) Number of elements removed.
Exceptions
1,2) Throws nothing.
3) Any exceptions thrown by the Compare object.
Complexity
Given an instance c of multimap:
1) Amortized constant
2) log(c.size()) + std::distance(first, last)
3) log(c.size()) + c.count(key)
Modifiers
swap( )
swaps the contents Parameters other - container to exchange the contents with Return value (none)
Exceptions
Any exception thrown by the swap of the Compare objects.
(until C++17) noexcept specification: noexcept(std::allocator_traits::is_always_equal::value && std::is_nothrow_swappable::value) (since C++17) Complexity Constant.
Modifiers
extract( )
extracts nodes from the container
Parameters
position - a valid iterator into this container
x - a key to identify the node to be extracted
Return value
A node handle that owns the extracted element, or empty node handle in case the element is not found in overload (2)
Complexity
1) amortized constant
2) log(a.size())
Modifiers
merge( )
splices nodes from another container Parameters source - compatible container to transfer the nodes from Return value (none)
Exceptions
Does not throw unless comparison throws.
Complexity
N*log(size()+N)), where N is source.size().
Lookup
count( )
returns the number of elements matching specific key
Parameters
key - key value of the elements to count
x - alternative value to compare to the keys
Return value
Number of elements with key that compares equivalent to key or x.
Complexity
Logarithmic in the size of the container plus linear in the number of the elements found.
Lookup
find( )
finds element with specific key
Parameters
key - key value of the element to search for
x - a value of any type that can be transparently compared with a key
Return value
Iterator to an element with key equivalent to key. If no such element is found, past-the-end (see end()) iterator is returned.
Complexity
Logarithmic in the size of the container.
Lookup
contains( )
checks if the container contains element with specific key
Parameters
key - key value of the element to search for
x - a value of any type that can be transparently compared with a key
Return value
true if there is such an element, otherwise false.
Complexity
Logarithmic in the size of the container.
Lookup equal_range( )
returns range of elements matching a specific key
Parameters
key - key value to compare the elements to
x - alternative value that can be compared to Key
Return value
std::pair containing a pair of iterators defining the wanted range: the first pointing to the first element that is not less than key and the second pointing to the first element greater than key.
If there are no elements not less than key, past-the-end (see end()) iterator is returned as the first element. Similarly if there are no elements greater than key, past-the-end iterator is returned as the second element.
Since emplace and unhinted insert always insert at the upper bound, the order of equivalent elements in the equal range is the order of insertion unless hinted insert or emplace_hint was used to insert an element at a different position. (since C++11)
Complexity
Logarithmic in the size of the container.
Lookup
lower_bound( )
returns an iterator to the first element not less than the given key
Parameters
key - key value to compare the elements to
x - alternative value that can be compared to Key
Return value
Iterator pointing to the first element that is not less than key. If no such element is found, a past-the-end iterator (see end()) is returned.
Complexity
Logarithmic in the size of the container.
Lookup
upper_bound( )
returns an iterator to the first element greater than the given key
Parameters
key - key value to compare the elements to
x - alternative value that can be compared to Key
Return value
Iterator pointing to the first element that is greater than key. If no such element is found, past-the-end (see end()) iterator is returned.
Complexity
Logarithmic in the size of the container.
Observers
key_comp( )
returns the function that compares keys
Parameters
(none)
Return value
The key comparison function object.
Complexity
Constant.
Observers
value_comp( )
returns the function that compares keys in objects of type value_type
Parameters
(none)
Return value
The value comparison function object.
Complexity
Constant.
