| CARVIEW |
Select Language
HTTP/1.1 301 Moved Permanently
Server: nginx
Date: Sat, 19 Jul 2025 10:19:13 GMT
Content-Type: text/html; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
Location: /reference/unordered_map/unordered_map/hash_function/
HTTP/1.1 200 OK
Server: nginx
Date: Sat, 19 Jul 2025 10:19:13 GMT
Content-Type: text/html; charset=utf-8
Transfer-Encoding: chunked
Connection: keep-alive
ETag: W/"8567-iOF72s7359HTJqTakLOgd34GgzE"
Content-Encoding: gzip
Returns the hash function object used by the unordered_map container.
The hash function is a unary function that takes an object of type key_type as argument and returns a unique value of type size_t based on it. It is adopted by the container on construction (see unordered_map's constructor for more info). By default, it is the default hashing function for the corresponding key type: hash<key_type>.
Member type hasher is the type of the hash function used by the container, defined in unordered_map as an alias of its third template parameter (Hash).
Possible output:
Notice how two similar strings yield quite different hash values.
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_map>
-
unordered_mapC++11
-
unordered_multimapC++11
unordered_map
-
unordered_map::~unordered_mapC++11
-
unordered_map::unordered_mapC++11
member functions
-
unordered_map::atC++11
-
unordered_map::beginC++11
-
unordered_map::bucketC++11
-
unordered_map::bucket_countC++11
-
unordered_map::bucket_sizeC++11
-
unordered_map::cbeginC++11
-
unordered_map::cendC++11
-
unordered_map::clearC++11
-
unordered_map::countC++11
-
unordered_map::emplaceC++11
-
unordered_map::emplace_hintC++11
-
unordered_map::emptyC++11
-
unordered_map::endC++11
-
unordered_map::equal_rangeC++11
-
unordered_map::eraseC++11
-
unordered_map::findC++11
-
unordered_map::get_allocatorC++11
-
unordered_map::hash_functionC++11
-
unordered_map::insertC++11
-
unordered_map::key_eqC++11
-
unordered_map::load_factorC++11
-
unordered_map::max_bucket_countC++11
-
unordered_map::max_load_factorC++11
-
unordered_map::max_sizeC++11
-
unordered_map::operator[]C++11
-
unordered_map::operator=C++11
-
unordered_map::rehashC++11
-
unordered_map::reserveC++11
-
unordered_map::sizeC++11
-
unordered_map::swapC++11
-
non-member overloads
-
operators (unordered_map)C++11
-
swap (unordered_map)C++11
-
- Reference
- <unordered_map>
- unordered_map
- hash_function
public member type
<unordered_map>
std::unordered_map::hash_function
hasher hash_function() const;
Get hash function
The hash function is a unary function that takes an object of type key_type as argument and returns a unique value of type size_t based on it. It is adopted by the container on construction (see unordered_map's constructor for more info). By default, it is the default hashing function for the corresponding key type: hash<key_type>.
Parameters
noneReturn Value
The hash function.Member type hasher is the type of the hash function used by the container, defined in unordered_map as an alias of its third template parameter (Hash).
Example
|
|
Possible output:
this: 671344778 thin: 3223852919 |
Notice how two similar strings yield quite different hash values.
Complexity
Constant.Iterator validity
No changes.See also
- unordered_map::key_eq
- Get key equivalence predicate (public member type)
- unordered_map::get_allocator
- Get allocator (public member function)
Home page | Privacy policy
© cplusplus.com, 2000-2025 - All rights reserved - v3.3.4s
Spotted an error? contact us
© cplusplus.com, 2000-2025 - All rights reserved - v3.3.4s
Spotted an error? contact us