unordered_map::Empty

Testes se sem elementos estão presentes.

bool empty() const;

Comentários

A função de membro retorna true para uma sequência vazia controlada.

Exemplo

 

// std_tr1__unordered_map__unordered_map_empty.cpp 
// compile with: /EHsc 
#include <unordered_map> 
#include <iostream> 
 
typedef std::tr1::unordered_map<char, int> Mymap; 
int main() 
    { 
    Mymap c1; 
 
    c1.insert(Mymap::value_type('a', 1)); 
    c1.insert(Mymap::value_type('b', 2)); 
    c1.insert(Mymap::value_type('c', 3)); 
 
// display contents " [c 3] [b 2] [a 1]" 
    for (Mymap::const_iterator it = c1.begin(); 
        it != c1.end(); ++it) 
        std::cout << " [" << it->first << ", " << it->second << "]"; 
    std::cout << std::endl; 
 
// clear the container and reinspect 
    c1.clear(); 
    std::cout << "size == " << c1.size() << std::endl; 
    std::cout << "empty() == " << std::boolalpha << c1.empty() << std::endl; 
    std::cout << std::endl; 
 
    c1.insert(Mymap::value_type('d', 4)); 
    c1.insert(Mymap::value_type('e', 5)); 
 
// display contents " [e 5] [d 4]" 
    for (Mymap::const_iterator it = c1.begin(); 
        it != c1.end(); ++it) 
        std::cout << " [" << it->first << ", " << it->second << "]"; 
    std::cout << std::endl; 
 
    std::cout << "size == " << c1.size() << std::endl; 
    std::cout << "empty() == " << std::boolalpha << c1.empty() << std::endl; 
 
    return (0); 
    } 
 

 [c, 3] [b, 2] [a, 1] size == 0 empty() == true   [e, 5] [d, 4] size == 2 empty() == false

Requisitos

Cabeçalho:<unordered_map>

Namespace: std::tr1

Consulte também

Referência

<unordered_map>

Classe unordered_map

unordered_map::dimensionar