Use subscript to change the value in a map : map subscript indexer « map multimap « C++ Tutorial

1. C++ Tutorial
2. map multimap
3. map subscript indexer

#include <iostream>
using std::cout;
using std::endl;

#include <map> // map class-template definition

int main()
{
   std::map< int, double, std::less< int > > pairs;

   pairs.insert( std::map< int, double, std::less< int > >::value_type( 15, 2.7 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 30, 111.11 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 0, 1010.1 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 10, 22.22 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 25, 33.333 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 0, 77.54 ) ); // dup ignored
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 20, 9.345 ) );
   pairs.insert( std::map< int, double, std::less< int > >::value_type( 15, 99.3 ) ); // dup ignored

   cout << "pairs contains:\nKey\tValue\n";

   // use const_iterator to walk through elements of pairs
   for ( std::map< int, double, std::less< int > >::const_iterator iter = pairs.begin();
      iter != pairs.end(); ++iter )
      cout << iter->first << '\t' << iter->second << '\n';

   pairs[ 25 ] = 9999.99; // use subscripting to change value for key 25

   cout << "\n\n\n";

   // use const_iterator to walk through elements of pairs
   for ( std::map< int, double, std::less< int > >::const_iterator iter = pairs.begin();
      iter != pairs.end(); ++iter )
      cout << iter->first << '\t' << iter->second << '\n';



   cout << endl;
   return 0;
}

pairs contains:
Key     Value
0       1010.1
10      22.22
15      2.7
20      9.345
25      33.333
30      111.11



0       1010.1
10      22.22
15      2.7
20      9.345
25      9999.99
30      111.11