What happens if you send some bitcoin to a non existing address?

[Sharky444]

If you type in an destination address instead of using copy/paste, and have a typo there, sending the bitcoins to this wrong (and lets say nonexisting) address. Do the bitcoins disappear forever (this is what I'm assuming), or is the blockchain rejecting this transaction?

[grue]

bitcoin addresses have a built in checksum. a typo will most likely* be rejected by the client and the funds won't be sent.

*1 in 4294967296 chance for typo to bypass check

[Sharky444]

Ok, so what happens if you send some Bitcoins to an Altcoin address that is based on Bitcoin? Since the checksum test should be the same (I guess many altcoins don't change that part of the code), does the transaction end up in nirvana?

[grue]

Ok, so what happens if you send some Bitcoins to an Altcoin address that is based on Bitcoin? Since the checksum test should be the same (I guess many altcoins don't change that part of the code), does the transaction end up in nirvana?

the network bits are different so it will also be rejected.

[Sharky444]

I've sent once some MemoryCoin 1.0 coins to a MegaCoin Address, and the coins just disappeared.

[Martijnvdc]

If you send coins to a "non existing" address, then that address has some coins, but nobody has it's private key. So the coins are lost since nobody can spend them.
By "non existing" i mean the private key is not known to someone.
An "existing" address would be an address with an actual owner who knows the private key.

[DarkHyudrA]

I've sent once some MemoryCoin 1.0 coins to a MegaCoin Address, and the coins just disappeared.

If it(the transaction) got accepted, get the priv key from the MegaCoin wallet and dump it to the MemoryCoin wallet.
Problem solved.

[zhinkk]

Well there can be two types of addresses in this situation:

An INVALID address, which means it's not the correct format for a bitcoin address, and the client should refuse to send it.

Or an UNCLAIMED address. By unclaimed I mean nobody has the private key for it. That means that your coins WILL be sent to the address (as long as it's valid), but nobody will be able to claim them since nobody has the private key for it.