C++ 将多个集合元素合并为一个集合
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Merge multiple sets elements in a single set
提问by codeHyman
I would like to know if there is any std library or boost tool to easily merge the contents of multiple sets into a single one.
我想知道是否有任何 std 库或 boost 工具可以轻松地将多个集合的内容合并为一个。
In my case I have some sets of ints which I would like to merge.
就我而言，我有一些想要合并的整数集。
回答by Nicola Musatti
You can do something like:
您可以执行以下操作：
std::set<int> s1;
std::set<int> s2;
// fill your sets
s1.insert(s2.begin(), s2.end());
回答by Antonio Pérez
Looks like you are asking for std::set_union.
看起来你是在要求std::set_union.
Example:
例子：
#include <set>
#include <algorithm>
std::set<int> s1;
std::set<int> s2;
std::set<int> s3;
// Fill s1 and s2
std::set_union(std::begin(s1), std::end(s1),
std::begin(s2), std::end(s2),
std::inserter(s3, std::begin(s3)));
// s3 now contains the union of s1 and s2
回答by Manohar Reddy Poreddy
With C++17, you can use mergefunction of setdirectly.
在 C++17 中，您可以直接使用 的merge函数set。
This is better, when you want the set2 elements extracted & inserted into set1 as part of merging.
当您希望将 set2 元素作为合并的一部分提取并插入到 set1 中时，这会更好。
Like below:
如下图：
set<int> set1{ 1, 2, 3 };
set<int> set2{ 1, 4, 5 };
// set1 has 1 2 3 set2 has 1 4 5
set1.merge(set2);
// set1 now has 1 2 3 4 5 set2 now has 1 (duplicates are left in the source, set2)
