hash_map::at

Article
07/29/2015

Note

This API is obsolete. The alternative is unordered_map Class.

Finds an element in a hash_map with a specified key value.

Type& at( 
   const Key& _Key 
); 
const Type& at( 
   const Key& _Key 
) const;

Parameters

Parameter	Description
_Key	The key value of the element that is to be found.

Return Value

A reference to the data value of the element found.

Remarks

If the argument key value is not found, then the function throws an object of class out_of_range Class.

In Visual C++ .NET 2003, members of the <hash_map> and <hash_set> header files are no longer in the std namespace, but rather have been moved into the stdext namespace. See The stdext Namespace for more information.

Example

// hash_map_at.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;
   
   // Insert data values
   hm1.insert ( cInt2Int ( 1, 10 ) );
   hm1.insert ( cInt2Int ( 2, 20 ) );
   hm1.insert ( cInt2Int ( 3, 30 ) );

   cout  << "The values of the mapped elements are:";
   for ( int i = 1 ; i <= hm1.size() ; i++ )
      cout << " " << hm1.at(i);
   cout << "." << endl;
}

Output

The values of the mapped elements are: 10 20 30.

Requirements

Header: <hash_map>

Namespace: stdext

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