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std:: hash <std::bitset>

From cppreference.net
C++
Utilities library
std::bitset
定义于头文件 <bitset>
template < std:: size_t N >
struct hash < std:: bitset < N >> ;
(C++11 起)

针对 std:: bitset < N > 的 std::hash 模板特化允许用户获取类型为 std:: bitset < N > 对象的哈希值。

示例

以下代码展示了哈希函数在多个位集上使用时可能的一种输出：

运行此代码 
#include <bitset>
#include <functional>
#include <iostream>
int main()
{
    std::bitset<4> b1{0}, b2{42};
    std::bitset<8> b3{0}, b4{42};
    std::hash<std::bitset<4>> hash_fn4;
    std::hash<std::bitset<8>> hash_fn8;
    using bin64 = std::bitset<64>;
    std::cout << std::hex
              << bin64{hash_fn4(b1)} << " = " << hash_fn4(b1) << '\n'
              << bin64{hash_fn4(b2)} << " = " << hash_fn4(b2) << '\n'
              << bin64{hash_fn8(b3)} << " = " << hash_fn8(b3) << '\n'
              << bin64{hash_fn8(b4)} << " = " << hash_fn8(b4) << '\n';
}

可能的输出： 

0110110100001001111011100010011011010101100001100011011000011001 = 6d09ee26d5863619
1111111101011100010110100000111000111110100000111011100011110000 = ff5c5a0e3e83b8f0
0110110100001001111011100010011011010101100001100011011000011001 = 6d09ee26d5863619
0101110000011100011110011010111011100110010000110100110001001101 = 5c1c79aee6434c4d

参见

(C++11)
哈希函数对象
(类模板)