hash_map::rehash (STL/CLR)

  • Article

Rebuilds the hash table.

    void rehash();

Remarks

The member function rebuilds the hash table, ensuring that hash_map::load_factor (STL/CLR)() <= hash_map::max_load_factor (STL/CLR). Otherwise, the hash table increases in size only as needed after an insertion. (It never automatically decreases in size.) You use it to adjust the size of the hash table.

Example

// cliext_hash_map_rehash.cpp 
// compile with: /clr 
#include <cliext/hash_map> 
 
typedef cliext::hash_map<wchar_t, int> Myhash_map; 
int main() 
    { 
    Myhash_map c1 = gcnew Myhash_map; 
    c1.insert(Myhash_map::make_value(L'a', 1)); 
    c1.insert(Myhash_map::make_value(L'b', 2)); 
    c1.insert(Myhash_map::make_value(L'c', 3)); 
 
// display contents " [a 1] [b 2] [c 3]" 
    for each (Myhash_map::value_type elem in c1) 
        System::Console::Write(" [{0} {1}]", elem->first, elem->second); 
    System::Console::WriteLine(); 
 
// inspect current parameters 
    System::Console::WriteLine("bucket_count() = {0}", c1.bucket_count()); 
    System::Console::WriteLine("load_factor() = {0}", c1.load_factor()); 
    System::Console::WriteLine("max_load_factor() = {0}", 
        c1.max_load_factor()); 
    System::Console::WriteLine(); 
 
// change max_load_factor and redisplay 
    c1.max_load_factor(0.25f); 
    System::Console::WriteLine("bucket_count() = {0}", c1.bucket_count()); 
    System::Console::WriteLine("load_factor() = {0}", c1.load_factor()); 
    System::Console::WriteLine("max_load_factor() = {0}", 
        c1.max_load_factor()); 
    System::Console::WriteLine(); 
 
// rehash and redisplay 
    c1.rehash(100); 
    System::Console::WriteLine("bucket_count() = {0}", c1.bucket_count()); 
    System::Console::WriteLine("load_factor() = {0}", c1.load_factor()); 
    System::Console::WriteLine("max_load_factor() = {0}", 
        c1.max_load_factor()); 
    return (0); 
    }

[a 1] [b 2] [c 3] bucket_count() = 16 load_factor() = 0.1875 max_load_factor() = 4 bucket_count() = 16 load_factor() = 0.1875 max_load_factor() = 0.25 bucket_count() = 128 load_factor() = 0.0234375 max_load_factor() = 0.25

Requirements

Header: <cliext/hash_map>

Namespace: cliext

See Also

Reference

hash_map (STL/CLR)

hash_map::bucket_count (STL/CLR)

hash_map::load_factor (STL/CLR)

hash_map::max_load_factor (STL/CLR)