C++ 字典可以在c++中使用吗
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Can dictionaries be used in c++
提问by Elliott
I have been looking up dictionaries in C# and they seem to be highly useful, and was wondering if it is possible to use them in C++ as I have tried to search for dictionaries in C++ but there doesn't seem to be an equivalent that I can find. Is there some sort of library that I could download and include to the project or is there a function which does the same thing just with a different name.
我一直在 C# 中查找字典，它们似乎非常有用，并且想知道是否可以在 C++ 中使用它们，因为我试图在 C++ 中搜索字典但似乎没有我可以找到。是否有某种库可以下载并包含到项目中，或者是否有一个函数可以使用不同的名称执行相同的操作。
回答by Anders Abel
There is a corresponding type in STL, that's called std::map.
STL 中有一个对应的类型，叫做std::map.
It has the same basic functionality as a .NET Dictionary, but the implementation is quite different. std::mapis internally based on a red-black tree datastructure, while Dictionaryuses a hash table internally.
它具有与 .NET Dictionary 相同的基本功能，但实现却大不相同。std::map内部基于红黑树数据结构，Dictionary内部使用哈希表。
If you're just looking for something with the same behaviour, std::mapwill do, but if you have large amounts of data you have to be aware of the different performance characteristics.
如果您只是在寻找具有相同行为的东西，std::map可以这样做，但是如果您有大量数据，则必须了解不同的性能特征。
回答by Angew is no longer proud of SO
There's std::mapfor logarithmic access time (usually based on a tree implementation) and std::unordered_map(since C++11) for expected constant, worst-case linear access time (usually based on a hashing implementation).
有std::map对数访问时间（通常基于树实现）和std::unordered_map（自 C++11 起）预期常数、最坏情况线性访问时间（通常基于散列实现）。
回答by Dharmendra Mishra
We can use map in C++ The basic format of using a map is -
我们可以在 C++ 中使用 map 使用 map 的基本格式是 -
std::map<Key_type, Value_Type> ;
Example -
例子 -
std::map<std::string,std::string> x = {{"A","ABC"},{"B","DEF"}}
