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Searches the container for an element with k as value and returns an iterator to it if found, otherwise it returns an iterator to unordered_set::end (the element past the end of the container).
Another member function, unordered_set::count, can be used to just check whether a particular element exists.
All iterators in an unordered_set have const access to the elements (even those whose type is not prefixed with const_): Elements can be inserted or removed, but not modified while in the container.
Member types iterator and const_iterator are forward iterator types. Both may be aliases of the same iterator type.
Possible output:
Worst case: linear in container size.
Reference
C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
-
<cfenv> (fenv.h)C++11
- <cfloat> (float.h)
-
<cinttypes> (inttypes.h)C++11
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
-
<cstdbool> (stdbool.h)C++11
- <cstddef> (stddef.h)
-
<cstdint> (stdint.h)C++11
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
-
<ctgmath> (tgmath.h)C++11
- <ctime> (time.h)
-
<cuchar> (uchar.h)C++11
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
-
<array>C++11
- <deque>
-
<forward_list>C++11
- <list>
- <map>
- <queue>
- <set>
- <stack>
-
<unordered_map>C++11
-
<unordered_set>C++11
- <vector>
-
Input/Output:
Multi-threading:
-
<atomic>C++11
-
<condition_variable>C++11
-
<future>C++11
-
<mutex>C++11
-
<thread>C++11
-
Other:
- <algorithm>
- <bitset>
-
<chrono>C++11
-
<codecvt>C++11
- <complex>
- <exception>
- <functional>
-
<initializer_list>C++11
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
-
<random>C++11
-
<ratio>C++11
-
<regex>C++11
- <stdexcept>
- <string>
-
<system_error>C++11
-
<tuple>C++11
-
<type_traits>C++11
-
<typeindex>C++11
- <typeinfo>
- <utility>
- <valarray>
<unordered_set>
-
unordered_multisetC++11
-
unordered_setC++11
unordered_set
-
unordered_set::~unordered_setC++11
-
unordered_set::unordered_setC++11
member functions
-
unordered_set::beginC++11
-
unordered_set::bucketC++11
-
unordered_set::bucket_countC++11
-
unordered_set::bucket_sizeC++11
-
unordered_set::cbeginC++11
-
unordered_set::cendC++11
-
unordered_set::clearC++11
-
unordered_set::countC++11
-
unordered_set::emplaceC++11
-
unordered_set::emplace_hintC++11
-
unordered_set::emptyC++11
-
unordered_set::endC++11
-
unordered_set::equal_rangeC++11
-
unordered_set::eraseC++11
-
unordered_set::findC++11
-
unordered_set::get_allocatorC++11
-
unordered_set::hash_functionC++11
-
unordered_set::insertC++11
-
unordered_set::key_eqC++11
-
unordered_set::load_factorC++11
-
unordered_set::max_bucket_countC++11
-
unordered_set::max_load_factorC++11
-
unordered_set::max_sizeC++11
-
unordered_set::operator=C++11
-
unordered_set::rehashC++11
-
unordered_set::reserveC++11
-
unordered_set::sizeC++11
-
unordered_set::swapC++11
-
non-member overloads
-
operators (unordered_set)C++11
-
swap (unordered_set)C++11
-
public member function
<unordered_set>
std::unordered_set::find
iterator find ( const key_type& k );const_iterator find ( const key_type& k ) const;
Get iterator to element
Another member function, unordered_set::count, can be used to just check whether a particular element exists.
All iterators in an unordered_set have const access to the elements (even those whose type is not prefixed with const_): Elements can be inserted or removed, but not modified while in the container.
Parameters
- k
- Key to be searched for.
Member type key_type is the type of the elements in the container. In unordered_set containers it is the same as value_type, defined as an alias of the class's first template parameter (Key).
Return value
An iterator to the element, if the specified value is found, or unordered_set::end if it is not found in the container.Member types iterator and const_iterator are forward iterator types. Both may be aliases of the same iterator type.
Example
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Possible output:
color? blue blue is in myset |
Complexity
Average case: constant.Worst case: linear in container size.
Iterator validity
No changes.See also
- unordered_set::count
- Count elements with a specific key (public member function)
- unordered_set::equal_range
- Get range of elements with a specific key (public member function)
- unordered_set::begin
- Return iterator to beginning (public member type)
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© cplusplus.com, 2000-2025 - All rights reserved - v3.3.4s
Spotted an error? contact us