C++ 访问集合中的元素？
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Access an element in a set?
提问by mr.bio
With a vector, I can do the following:
使用向量，我可以执行以下操作：
vector<int> myvec (4,100);
int first = myvec.at(0);
I have the following set:
我有以下设置：
set<int> myset;
myset.insert(100);
int setint = ????
How can I access the the element I inserted in the set?
如何访问我插入到集合中的元素？
采纳答案by Michael Kristofik
set<int>::iterator iter = myset.find(100);
if (iter != myset.end())
{
int setint = *iter;
}
回答by wilhelmtell
You can't access set elements by index. You have to access the elements using an iterator.
您不能通过索引访问集合元素。您必须使用迭代器访问元素。
set<int> myset;
myset.insert(100);
int setint = *myset.begin();
If the element you want is not the first one then advance the iterator to that element. You can look in a set to see if an element exists, using set<>::find(), or you can iterate over the set to see what elements are there.
如果您想要的元素不是第一个元素，则将迭代器推进到该元素。您可以查看集合以查看元素是否存在，使用set<>::find()，或者您可以遍历集合以查看存在哪些元素。
回答by Rafsan
You can also use this approach :
您也可以使用这种方法：
set<int>:: iterator it;
for( it = s.begin(); it!=s.end(); ++it){
int ans = *it;
cout << ans << endl;
}
