unordered_set::load_factor

發行項
06/09/2015

計數平均項目每個 Bucket。

float load_factor() const;

備註

成員函式傳回 (float)unordered_set::size() / (float)unordered_set::bucket_count()，項目的平均數目。每個 Bucket。

範例

// std_tr1__unordered_set__unordered_set_load_factor.cpp 
// compile with: /EHsc 
#include <unordered_set> 
#include <iostream> 
 
typedef std::unordered_set<char> Myset; 
int main() 
    { 
    Myset c1; 
 
    c1.insert('a'); 
    c1.insert('b'); 
    c1.insert('c'); 
 
// display contents " [c] [b] [a]" 
    for (Myset::const_iterator it = c1.begin(); 
        it != c1.end(); ++it) 
        std::cout << " [" << *it << "]"; 
    std::cout << std::endl; 
 
// inspect current parameters 
    std::cout << "bucket_count() == " << c1.bucket_count() << std::endl; 
    std::cout << "load_factor() == " << c1.load_factor() << std::endl; 
    std::cout << "max_bucket_count() == " 
        << c1.max_bucket_count() << std::endl; 
    std::cout << "max_load_factor() == " 
        << c1.max_load_factor() << std::endl; 
    std::cout << std::endl; 
 
// change max_load_factor and redisplay 
    c1.max_load_factor(0.10f); 
    std::cout << "bucket_count() == " << c1.bucket_count() << std::endl; 
    std::cout << "load_factor() == " << c1.load_factor() << std::endl; 
    std::cout << "max_bucket_count() == " 
        << c1.max_bucket_count() << std::endl; 
    std::cout << "max_load_factor() == " 
        << c1.max_load_factor() << std::endl; 
    std::cout << std::endl; 
 
// rehash and redisplay 
    c1.rehash(100); 
    std::cout << "bucket_count() == " << c1.bucket_count() << std::endl; 
    std::cout << "load_factor() == " << c1.load_factor() << std::endl; 
    std::cout << "max_bucket_count() == " 
        << c1.max_bucket_count() << std::endl; 
    std::cout << "max_load_factor() == " 
        << c1.max_load_factor() << std::endl; 
    std::cout << std::endl; 
 
    return (0); 
    }