multimap::lower_bound

傳回 Iterator 至具有索引鍵等於或大於指定的索引鍵 multimap 的第一個項目。

iterator lower_bound(
   const Key& _Key
);
const_iterator lower_bound(
   const Key& _Key
) const;

參數

• _Key
  引數的索引鍵使用一個項目來排序鍵來比較要搜尋的 multimap 的。

傳回值

處理一個項目位置 multimap 與索引鍵等於或大於引數金鑰，或是處理成功最後一個項目的位置。 const_iterator 或 multimap 的 Iterator，如果沒有相符的索引鍵中找到。

如果 lower_bound 的傳回值指派給 const_iterator，無法修改 multimap 物件。 如果 lower_bound 的傳回值指派給 iterator，可以修改 multimap 物件。

範例

// multimap_lower_bound.cpp
// compile with: /EHsc
#include <map>
#include <iostream>

int main( )
{
   using namespace std;
   multimap <int, int> m1;
   multimap <int, int> :: const_iterator m1_AcIter, m1_RcIter;
   typedef pair <int, int> Int_Pair;

   m1.insert ( Int_Pair ( 1, 10 ) );
   m1.insert ( Int_Pair ( 2, 20 ) );
   m1.insert ( Int_Pair ( 3, 20 ) );
   m1.insert ( Int_Pair ( 3, 30 ) );

   m1_RcIter = m1.lower_bound( 2 );
   cout << "The element of multimap m1 with a key of 2 is: "
        << m1_RcIter -> second << "." << endl;

   m1_RcIter = m1.lower_bound( 3 );
   cout << "The first element of multimap m1 with a key of 3 is: "
        << m1_RcIter -> second << "." << endl;

   // If no match is found for the key, end( ) is returned
   m1_RcIter = m1.lower_bound( 4 );

   if ( m1_RcIter == m1.end( ) )
      cout << "The multimap m1 doesn't have an element "
              << "with a key of 4." << endl;
   else
      cout << "The element of multimap m1 with a key of 4 is: "
                << m1_RcIter -> second << "." << endl;

   // The element at a specific location in the multimap can be
   // found using a dereferenced iterator addressing the location
   m1_AcIter = m1.end( );
   m1_AcIter--;
   m1_RcIter = m1.lower_bound( m1_AcIter -> first );
   cout << "The first element of m1 with a key matching\n"
        << "that of the last element is: "
        << m1_RcIter -> second << "." << endl;

   // Note that the first element with a key equal to
   // the key of the last element is not the last element
   if ( m1_RcIter == --m1.end( ) )
      cout << "This is the last element of multimap m1."
           << endl;
   else
      cout << "This is not the last element of multimap m1."
           << endl;
}

需求

標題: <map>

命名空間: std

請參閱

參考

multimap Class

標準樣板程式庫