public member function
<set>
iterator begin();const_iterator begin() const;
iterator begin() noexcept;const_iterator begin() const noexcept;
Return iterator to beginning
Returns an iterator referring to the first element in the multiset container.
Because multiset containers keep their elements ordered at all times,beginpoints to the element that goes first following the container's sorting criterion.
If the container is empty, the returned iterator value shall not be dereferenced.
返回值
指向容器中第一個元素的迭代器。
If the multiset object is const-qualified, the function returns aconst_iterator。否則，它返回一個iterator.
成員型別iterator和const_iteratorare bidirectional iterator types pointing to elements.
示例
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// multiset::begin/end
#include <iostream>
#include <set>
int main ()
{
int myints[] = {42,71,71,71,12};
std::multiset<int> mymultiset (myints,myints+5);
std::multiset<int>::iterator it;
std::cout << "mymultiset contains:";
for (std::multiset<int>::iterator it=mymultiset.begin(); it!=mymultiset.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
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輸出
mymultiset contains: 12 42 71 71 71
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資料競爭
訪問容器（const 和非 const 版本都不會修改容器）。
同時訪問 multiset 的元素是安全的。
異常安全
無異常保證：此成員函式從不丟擲異常。
還可以保證返回的迭代器的複製構造或賦值永遠不會引發異常。