Cast on a "float" sequence throws invalidcastexception

Cause: the cast method only supports reference and boxing conversions. Use select instead:

That is to say, the cast <> () method only supports packing and unpacking, and other forced type conversion is not supported.

For example, if you want to complete the following code, an exception will be thrown:

Static void main (string [] ARGs)
{
Hashtable ST = new hashtable ();
St. Add ("A", 12 );
St. Add ("B", 13 );
St. Add ("C", 14 );
Double sum = ST. Values. Cast <float> (). sum ();
}

This is acceptable:

Hashtable ST = new hashtable ();
St. Add ("A", 12f );
St. Add ("B", 13f );
St. Add ("C", 14f );
Double sum = ST. Values. Cast <float> (). sum ();