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operator< (map)

Tests if the map object on the left side of the operator is less than the map object on the right side.

bool operator<(
   const map <Key, Type, Traits, Allocator>& _Left,
   const map <Key, Type, Traits, Allocator>& _Right
);

Parameters

  • _Left
    An object of type map.

  • _Right
    An object of type map.

Return Value

true if the map on the left side of the operator is strictly less than the map on the right side of the operator; otherwise false.

Remarks

The comparison between map objects is based on a pairwise comparison of their elements. The less-than relationship between two objects is based on a comparison of the first pair of unequal elements.

Example

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

int main( )
{
   using namespace std;
   map<int, int> m1, m2, m3;
   int i;
   typedef pair<int, int> Int_Pair;

   for ( i = 1 ; i < 3 ; i++ )
   {
      m1.insert ( Int_Pair ( i, i ) );
      m2.insert ( Int_Pair ( i, i * i ) );
      m3.insert ( Int_Pair ( i, i - 1 ) );
   }

   if ( m1 < m2 )
      cout << "The map m1 is less than the map m2." << endl;
   else
      cout << "The map m1 is not less than the map m2." << endl;

   if ( m1 < m3 )
      cout << "The map m1 is less than the map m3." << endl;
   else
      cout << "The map m1 is not less than the map m3." << endl;
}

The map m1 is less than the map m2.
The map m1 is not less than the map m3.

Requirements

Header: <map>

Namespace: std

See Also

Concepts

<map> Members

Standard Template Library