stl:map:empty

Syntax:

    #include <map>
    bool empty() const;

The empty() function returns true if the map has no elements, false otherwise.

For example, the following code uses empty() as the stopping condition on a while loop to clear a map and display its contents in order:

    struct strCmp {
      bool operator()( const char* s1, const char* s2 ) const {
        return strcmp( s1, s2 ) < 0;
      }
    };
 
    ...
 
    map<const char*, int, strCmp> ages;
    ages["Homer"] = 38;
    ages["Marge"] = 37;
    ages["Lisa"] = 8;
    ages["Maggie"] = 1;
    ages["Bart"] = 11;
 
    while( !ages.empty() ) {
      cout << "Erasing: " << (*ages.begin()).first << ", " << (*ages.begin()).second << endl;
      ages.erase( ages.begin() );
    }

When run, the above code displays:

    Erasing: Bart, 11
    Erasing: Homer, 38
    Erasing: Lisa, 8
    Erasing: Maggie, 1
    Erasing: Marge, 37

Related Topics: begin, erase, size