set::equal_range

發行項
06/09/2015

傳回一組 Iterator 分別為一組的第一個項目與大於或等於指定之索引鍵的索引鍵與集合中的第一個項目與大於按鍵。

pair <const_iterator, const_iterator> equal_range ( 
   const Key& _Key 
) const; 
pair <iterator, iterator> equal_range ( 
   const Key& _Key 
);

參數

_Key
引數索引鍵與項目的排序鍵會比較搜尋的集合中。

傳回值

第一個是 lower_bound 索引鍵和第二個的一組 Iterator 是索引鍵的 upper_bound 。

若要存取一個至 pr 的第一個 Iterator 的成員函式傳回，則使用 pr。first和取值下限 Iterator，使用* (pr。first)。若要存取一個至 pr 的第二個 Iterator 之成員函式傳回，則使用 pr。second和取值上限 Iterator，使用* (pr。second)。

範例

// set_equal_range.cpp
// compile with: /EHsc
#include <set>
#include <iostream>

int main( )
{
   using namespace std;
   typedef set<int, less< int > > IntSet;
   IntSet s1;
   set <int, less< int > > :: const_iterator s1_RcIter;
   
   s1.insert( 10 );
   s1.insert( 20 );
   s1.insert( 30 );

   pair <IntSet::const_iterator, IntSet::const_iterator> p1, p2;
   p1 = s1.equal_range( 20 );

   cout << "The upper bound of the element with "
        << "a key of 20 in the set s1 is: "
        << *(p1.second) << "." << endl;

   cout << "The lower bound of the element with "
        << "a key of 20 in the set s1 is: "
        << *(p1.first) << "." << endl;

   // Compare the upper_bound called directly 
   s1_RcIter = s1.upper_bound( 20 );
   cout << "A direct call of upper_bound( 20 ) gives "
        << *s1_RcIter << "," << endl
        << "matching the 2nd element of the pair"
        << " returned by equal_range( 20 )." << endl;

   p2 = s1.equal_range( 40 );

   // If no match is found for the key,
   // both elements of the pair return end( )
   if ( ( p2.first == s1.end( ) ) && ( p2.second == s1.end( ) ) )
      cout << "The set s1 doesn't have an element "
           << "with a key less than 40." << endl;
   else
      cout << "The element of set s1 with a key >= 40 is: "
           << *(p1.first) << "." << endl;
}