HashTables and scoping

[Roger Webb]

Hey All,

I cant VERIFY this, but it makes sense so I thought I'd trow up my theory
and see if it made sense to any of you... and then ask how to get around it.
hehe

I've got a Class1[] that I'm wanting to load into a hash table, so, I
basically (at this point) run through a loop and do a
Hashtable.Add(Class1[index].key,Class1[index])

However, later when I try to get out the value out of the HashTable... The
value is null.

I'm thinking this is because the array that initially had the values has
gone out of scope .. and the hashtable only stored a reference to the
object.. so now, the refence is null. If this is true, how do I get
around that? If it is not true, does anyone know why I'm not getting my
values out?

- Roger

[Nicholas Paldino [.NET/C# MVP]]

Roger,

This is not the case. When you assign Class1[index] to the hashtable,
the hashtable holds a reference to the object in the array. If the array
goes out of scope, as long as the hashtable is in scope, then the references
are still valid.

It is something else that is causing the values in the hashtable to be
null.

The only things I can think of are that the value at Class1[index] is
already null, and it's null when it goes in, or there is an explicit setting
of the value for that key to null.

Can you provide a sample project which shows the error?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Roger Webb" <rw***@nos.twia.org> wrote in message
news:Oq**************@TK2MSFTNGP10.phx.gbl...

Hey All,

I cant VERIFY this, but it makes sense so I thought I'd trow up my theory
and see if it made sense to any of you... and then ask how to get around
it.
hehe

I've got a Class1[] that I'm wanting to load into a hash table, so, I
basically (at this point) run through a loop and do a
Hashtable.Add(Class1[index].key,Class1[index])

However, later when I try to get out the value out of the HashTable... The
value is null.

I'm thinking this is because the array that initially had the values has
gone out of scope .. and the hashtable only stored a reference to the
object.. so now, the refence is null. If this is true, how do I get
around that? If it is not true, does anyone know why I'm not getting my
values out?

- Roger

[Roger Webb]

I know that the values going in are non-null, mainly becasue the key value
is a property of the class being added. So I will investigate that it is
beign set null somewhere that I am unaware of.

Thanks for the reply.

- Roger
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:O9**************@TK2MSFTNGP15.phx.gbl...

Roger,

This is not the case. When you assign Class1[index] to the hashtable,
the hashtable holds a reference to the object in the array. If the array
goes out of scope, as long as the hashtable is in scope, then the references are still valid.

It is something else that is causing the values in the hashtable to be
null.

The only things I can think of are that the value at Class1[index] is
already null, and it's null when it goes in, or there is an explicit setting of the value for that key to null.

Can you provide a sample project which shows the error?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Roger Webb" <rw***@nos.twia.org> wrote in message
news:Oq**************@TK2MSFTNGP10.phx.gbl...

Hey All,

I cant VERIFY this, but it makes sense so I thought I'd trow up my theory and see if it made sense to any of you... and then ask how to get around
it.
hehe

I've got a Class1[] that I'm wanting to load into a hash table, so, I
basically (at this point) run through a loop and do a
Hashtable.Add(Class1[index].key,Class1[index])

However, later when I try to get out the value out of the HashTable... The value is null.

I'm thinking this is because the array that initially had the values has
gone out of scope .. and the hashtable only stored a reference to the
object.. so now, the refence is null. If this is true, how do I get
around that? If it is not true, does anyone know why I'm not getting my
values out?

- Roger