set::lower_bound

發行項
03/27/2013

傳回 Iterator 加入至集合的第一個項目具有等於或大於指定的索引鍵。

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

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之集合中的。

傳回值

處理一個項目位置中的具有索引鍵等於或大於這個金鑰的引數或解決成功最後一個項目的位置。這個集合的列舉值或 const_iterator ，如果符合沒有索引鍵中找到。

範例

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

int main( )
{
   using namespace std;
   set <int> s1;
   set <int> :: const_iterator s1_AcIter, s1_RcIter;
   
   s1.insert( 10 );
   s1.insert( 20 );
   s1.insert( 30 );

   s1_RcIter = s1.lower_bound( 20 );
   cout << "The element of set s1 with a key of 20 is: "
        << *s1_RcIter << "." << endl;

   s1_RcIter = s1.lower_bound( 40 );

   // If no match is found for the key, end( ) is returned
   if ( s1_RcIter == s1.end( ) )
      cout << "The set s1 doesn't have an element "
           << "with a key of 40." << endl;
   else
      cout << "The element of set s1 with a key of 40 is: "
           << *s1_RcIter << "." << endl;

   // The element at a specific location in the set can be found 
   // by using a dereferenced iterator that addresses the location
   s1_AcIter = s1.end( );
   s1_AcIter--;
   s1_RcIter = s1.lower_bound( *s1_AcIter );
   cout << "The element of s1 with a key matching "
        << "that of the last element is: "
        << *s1_RcIter << "." << endl;
}