shared memory not same address

[herbey]

hi,

I want a server process to create a segment of shared memory and a client process to be able to access it. I am using the following code.
Server:
void *shared_memory=(void *)0;
shmid=shmget((key_t)998,1024,0666 | IPC_CREAT);
shared_memory=shmat(shmid,(void *)0,0);

Client
shmid=shmget((key_t)998,1024,0666);
shared_memory=shmat(shmid,(void *)0,0);

when in each process I display the address of memory to which shmat is attaching each process, the values are different,

what am I doing wrong? I would think that the addresses returned by shmat are the same for both the client and server processes, thanks

[S6k9GNh0]

Weren't sockets made for this very purpose? To transmit data between processes?

[choisum]

man shmat

[choisum]

Weren't sockets made for this very purpose? To transmit data between processes?

Yes, between processes on different machines. However, there's no need to pay serialization costs if all processes are on the same machine. In some applications this matters.

[choisum]

all processes are on the same machine

oth, why not just use threads here?