hash_map::value_type

注意事項
這個 API 已經過時。替代方案是 unordered_map 類別。

表示物件型別的型別在 hash_map 儲存。

typedef pair<const Key, Type> value_type;

備註

使用非常數 Iterator 或參考，，，因為關聯的容器的金鑰不可以變更value_type 宣告為 pair*<const key_type，而不是 mapped_type>pair <key_type, mapped_type> 。*

在 Visual C++ .NET 2003 中， <hash_map> 和 <hash_set> 標頭檔的成員不在 std 命名空間中，而是移至 stdext 命名空間。 如需詳細資訊，請參閱 stdext 命名空間。

範例

// hash_map_value_type.cpp
// compile with: /EHsc
#include <hash_map>
#include <iostream>

int main( ) 
{
   using namespace std;
   using namespace stdext;
   typedef pair <const int, int> cInt2Int;
   hash_map <int, int> hm1;
   hash_map <int, int> :: key_type key1;
   hash_map <int, int> :: mapped_type mapped1;
   hash_map <int, int> :: value_type value1;
   hash_map <int, int> :: iterator pIter;
   
   // value_type can be used to pass the correct type
   // explicitely to avoid implicit type conversion
   hm1.insert ( hash_map <int, int> :: value_type ( 1, 10 ) );

   // Compare other ways to insert objects into a hash_map
   hm1.insert ( cInt2Int ( 2, 20 ) );
   hm1[ 3 ] = 30;

   // Initializing key1 and mapped1
   key1 = ( hm1.begin( ) -> first );
   mapped1 = ( hm1.begin( ) -> second );

   cout << "The key of first element in the hash_map is "
        << key1 << "." << endl;

   cout << "The data value of first element in the hash_map is "
        << mapped1 << "." << endl;

   // The following line would cause an error because
   // the value_type is not assignable
   // value1 = cInt2Int ( 4, 40 );

   cout  << "The keys of the mapped elements are:";
   for ( pIter = hm1.begin( ) ; pIter != hm1.end( ) ; pIter++ )
      cout << " " << pIter -> first;
   cout << "." << endl;

   cout  << "The values of the mapped elements are:";
   for ( pIter = hm1.begin( ) ; pIter != hm1.end( ) ; pIter++ )
      cout << " " << pIter -> second;
   cout << "." << endl;
}

需求

標頭檔: <hash_map>

**命名空間：**stdext

請參閱

參考

hash_map 類別

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