map::lower_bound

Returns an iterator to the first element in a map with a key value that is equal to or greater than that of a specified key.

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

Parameters

• _Key
  The argument key value to be compared with the sort key of an element from the map being searched.

Return Value

An iterator or const_iterator that addresses the ___location of an element in a map that with a key that is equal to or greater than the argument key, or that addresses the ___location succeeding the last element in the map if no match is found for the key.

If the return value of lower_bound is assigned to a const_iterator, the map object cannot be modified. If the return value of lower_bound is assigned to an iterator, the map object can be modified.

Example

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

int main( )
{
   using namespace std;   
   map <int, int> m1;
   map <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, 30 ) );

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

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

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

   // The element at a specific ___location in the map 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 element of m1 with a key matching "
        << "that of the last element is: "
        << m1_RcIter -> second << "." << endl;
}

The first element of map m1 with a key of 2 is: 20.
The map m1 doesn't have an element with a key of 4.
The element of m1 with a key matching that of the last element is: 30.

Requirements

Header: <map>

Namespace: std

See Also

Reference

map Class

Standard Template Library