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bool operator==(point const& p1, point const& p2) { return p1.x == p2.x && p1.y == p2.y; }
bool operator==(point const& p1, point const& p2) { return p1.x == p2.x &&& p1.y == p2.y; }
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```cpp struct point { int x; int y; };
```cpp struct point { int x; int y; };
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Since the default hash function is link:../../../../container_hash/index.html[Boost.Hash^], we can extend it to support the type so that the hash function doesn't need to be explicitly given:
Since the default hash function is由于默认哈希函数是 link:../../../../container_hash/index.html[Boost.Hash^], we can extend it to support the type so that the hash function doesn't need to be explicitly given:，我们可以扩展它以支持该类型，从而无需显式给出哈希函数：
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boost::unordered_multiset<point, point_hash> points; ```
boost::unordered_multiset<point, point_hash=""> points; ```</point,>
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struct point_hash { std::size_t operator()(point const& p) const { std::size_t seed = 0; boost::hash_combine(seed, p.x); boost::hash_combine(seed, p.y); return seed; } };
struct point_hash { std::size_t operator()(point const&amp; p) const { std::size_t seed = 0; boost::hash_combine(seed, p.x); boost::hash_combine(seed, p.y); return seed; } };
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bool operator==(point const& p1, point const& p2) { return p1.x == p2.x && p1.y == p2.y; }
bool operator==(point const&amp; p1, point const&amp; p2) { return p1.x == p2.x &&amp;&amp; p1.y == p2.y; }
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```cpp struct point { int x; int y; };
```cpp struct point { int x; int y; };
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Similarly, a custom hash function can be used for custom types:
Similarly, a custom hash function can be used for custom types:类似地，自定义类型也可使用自定义哈希函数：
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Custom Types
Custom Types自定义类型
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predicates, especially if you're using a function pointer. If you compare two containers with different equality predicates then the result is undefined. For most stateless function objects this is impossible - since you can only compare objects with the same equality predicate you know the equality predicates must be equal. But if you're using function pointers or a stateful equality predicate (e.g. `boost::function`) then you can get into trouble.
predicates, especially if you're using a function pointer. If you compare two containers with different equality predicates then the result is undefined. For most stateless function objects this is impossible - since you can only compare objects with the same equality predicate you know the equality predicates must be equal. But if you're using function pointers or a stateful equality predicate (e.g. `boost::function`) then you can get into trouble.在使用自定义相等谓词（特别是函数指针）时请务必小心。如果你用不同的相等谓词比较两个容器，结果是未定义的。对于大多数无状态函数对象而言，这种情况不可能发生——因为你只能使用相同的相等谓词来比较对象，所以两个相等谓词必然相等。但如果你使用的是函数指针或有状态的相等谓词（例如 boost::function），则可能会遇到问题。
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Be careful when using the equality (`==`) operator with custom equality
Be careful when using the equality (`==`) operator with custom equality在使用自定义相等谓词时，请谨慎使用相等（==）运算符
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This is a simplified version of the example at link:../../../examples/case_insensitive.hpp[/libs/unordered/examples/case_insensitive.hpp^] which supports other locales and string types.
This is a simplified version of the example at这是 link:../../../examples/case_insensitive.hpp[/libs/unordered/examples/case_insensitive.hpp^] which supports other locales and string types.处示例的简化版本，该示例支持其他区域设置和字符串类型。
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Which you can then use in a case insensitive dictionary: ```cpp boost::unordered_map<std::string, int, ihash, iequal_to> idictionary; ```
Which you can then use in a case insensitive dictionary: 然后你可以在不区分大小写的字典中使用它：```cpp boost::unordered_map<std::string, int,="" ihash,="" iequal_to=""> idictionary; ```</std::string,>
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return seed; } }; ```
return seed; } }; ```
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for(std::string::const_iterator it = x.begin(); it != x.end(); ++it) { boost::hash_combine(seed, std::toupper(*it, locale)); }
for(std::string::const_iterator it = x.begin(); it != x.end(); ++it) { boost::hash_combine(seed, std::toupper(*it, locale)); }
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struct ihash { std::size_t operator()(std::string const& x) const { std::size_t seed = 0; std::locale locale;
struct ihash { std::size_t operator()(std::string const&amp; x) const { std::size_t seed = 0; std::locale locale;
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```cpp struct iequal_to { bool operator()(std::string const& x, std::string const& y) const { return boost::algorithm::iequals(x, y, std::locale()); } };
```cpp struct iequal_to { bool operator()(std::string const&amp; x, std::string const&amp; y) const { return boost::algorithm::iequals(x, y, std::locale()); } };
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If you wish to use a different equality function, you will also need to use a matching hash function. For example, to implement a case insensitive dictionary you need to define a case insensitive equality predicate and hash function:
If you wish to use a different equality function, you will also need to use a matching hash function. For example, to implement a case insensitive dictionary you need to define a case insensitive equality predicate and hash function:```cpp
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There is an link:../../../examples/fnv1.hpp[implementation of FNV-1a^] in the examples directory.
There is an link:examples 目录中有一个链接：../../../examples/fnv1.hpp[implementation of FNV-1a^] in the examples directory.
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```cpp boost::unordered_map<std::string, int, hash::fnv_1a> dictionary; ```
```cpp boost::unordered_map<std::string, int,="" hash::fnv_1a=""> dictionary; ```</std::string,>
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