multimap::lower_bound

返回迭代器到与键等于或大于指定的键的基于的第一个元素。

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

参数

• _Key
  参数键与一个元素的排序关键字进行比较从要搜索的基于的。

返回值

解决一个元素位置在基于的密钥等于或大于参数键，或者解决成功最后一个元素的位置在基于的迭代器或 const_iterator，如果与未作为项中。

如果 lower_bound 的返回值赋给 const_iterator，不能修改基于对象。如果 lower_bound 的返回值赋给 iterator，可以修改基于对象。

示例

// 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;
}

要求

标头: <map>

命名空间: std

请参见

参考

multimap Class

标准模板库