地图和多图：内存使用/管理差异？ [英] Map and multimap : memory usage / management differences?
问题描述
我写了一个程序，必须读取一个大文件与操作符>>，计数一些东西，并插入数据（字符串和int）在多图。
问题是程序崩溃，它似乎是一个内存问题（它适用于小文件）。
我认为它达到了Windows的内存分配限制。
I wrote a program that have to read a big file with operator>> , count some stuff and insert datas (string and int) in a multimap. The problem is that the program crashes and it seems to be a memory problem (it works well with small files). I think that it reaches the memory allocation limit of Windows.
我试过：
我做了一个32位和一个64位版本。
如你所知，Windows有一个内存分配限制，对于32位和64位内部版本是不一样的。
两个都崩溃了。
我查看任务管理器的性能选项卡以观察内存消耗。
32位：每次达到5.3 GB时程序崩溃。
64位：程序的内存消耗持续增加，直到它到达系统的整个RAM并崩溃。
What I tried : I made a 32-bit and an 64-bit versions. As you know, Windows has a memory allocation limit that is not the same for 32bits and 64bits builds. With both it crashes. I looked the performance tab of the task manager to observe the memory consumption. 32-bit : the program crashes every time it reaches 5.3 GB. 64-bit : the memory consumption of the program continually increases until it reaches the whole RAM of the system and crashes.
我试图用一个映射代替a multimap：程序永远不会崩溃，并在程序执行时保持稳定在大约3.5 GB（32位和64位版本）。
I tried with a map instead of a multimap : the program never crashes and stay stable at roughly 3.5 GB (32-bit and 64-bit builds) all along the program execution.
如果在内存使用或内存管理方面map和multimap之间有区别？
或者是因为map不允许重复键？
So, do you know if there is a difference between map and multimap in terms of memory usage or memory management ? Or is it just because map do not allows duplicate keys ?
推荐答案
您是否已阅读说明？
std :: map是一个排序关联容器，其中包含具有唯一键的键值对。键使用比较函数Compare进行排序。
std::map is a sorted associative container that contains key-value pairs with unique keys. Keys are sorted by using the comparison function Compare.
返回值：
1-2）返回一个由迭代器组成的插入元素（或阻止插入的元素）
Return value: 1-2) Returns a pair consisting of an iterator to the inserted element (or to the element that prevented the insertion) and a bool denoting whether the insertion took place.
您不能有两个相同的键，因此您可以使用相同的键重写值不分配任何新空间。
You cannot have two same keys, so you overwrite values under the same key, you don't allocate any new space.
Multimap一个包含键值对的排序列表的关联容器。
Multimap is an associative container that contains a sorted list of key-value pairs.
std :: multimap :: insert 无法失败一个迭代器因为，它总是添加新的关联。因此在循环中在同一个键下添加项将分配新的内存。
std::multimap::insert cannot "fail", it always return an iterator because, it always adds new association. So adding items under the same key in a loop will allocate new memory.
对于每个多容器（集合，无序映射， / em>）。它们在语义上不同。
Similar is true for every multi-container (set, unordered map, etc.). They are semantically different.
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