multimap::lower_bound

傳回 Iterator 置於與索引鍵等於或大於指定之索引鍵的多重對應的第一個項目。

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

參數

• _Key
  引數索引鍵與項目的排序鍵會比較搜尋字串的多個對應的。

傳回值

處理一個項目位置在多重對應的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在多重對應的 Iterator 則為 const_iterator ，如果遊戲不為索引鍵中找到。

如果傳回值 lower_bound 給 const_iterator，無法修改多重對應物件。 如果 lower_bound 的傳回值指派給 iterator，可以修改多重對應物件。

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

標頭：<map>

命名空間: std

請參閱

參考

multimap 類別

標準樣板程式庫