我最初开始使用 std::multimap 来存储具有相同键的多个值，但后来我发现它不能保留具有相同键的值之间的插入顺序。 这个答案声称可以通过boost::multi_index::multi_index_container，但没有给出示例。浏览文档，没有该用法的示例，而且我无法弄清楚您应该如何使用这个东西。我本来以为很少使用的 boost 库会提供糟糕的文档，但这是最重要的。任何人都可以向我指出一个教程或示例，以显示它按照我想要的方式使用，或者甚至可以自己提供一个示例吗？
I initially started out using a std::multimap to store many values with the same key, but then I discovered that it doesn't preserve the insertion order among values with the same key. This answer claims it can be done with boost::multi_index::multi_index_container, but gives no example. Looking through the docs, there are no examples of that usage, and I can't make heads or tails of how you're supposed to use this thing. I have come to expect poor documentation from the lesser-used boost libraries, but this takes the cake. Can anyone point me to a tutorial or example that shows it used the way I want, or perhaps even provide an example themselves?
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您可以通过使用
boost::multi_index和两个索引来实现此目的：ordered_non_unique（允许具有相同键的值）和random_access（这将保持插入顺序） 。You could achieve this by using
boost::multi_indexwith two indices:ordered_non_unique(which allows values with the same key) andrandom_access(which will keep the insertion order).@Kirill：很好
或
的答案。我怀疑 Boost 的 random_access 可能非常慢，因为它会强制所有键的所有字符串都维护在一个连续的结构中。而提问者只是希望在每个键的映射值集中保留顺序。
How about a
or
@Kirill: Good answer. I suspect Boost's random_access can be quite slow, as it will force all strings for all keys to be maintained in a single contiguous structure. Whereas the questioner simply wants order to be preserved within each key's set of mapped values.