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Full Discussion: help with shared memory
Top Forums Programming help with shared memory Post 302113353 by ddx08 on Thursday 5th of April 2007 10:57:08 AM
Old 04-05-2007
help with shared memory

what i want to do is have an int that can been written into by 2 processes but my code doesn't seem to work.

Code:
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include<stdio.h>
#define KEY1 (1492)
int main()
{

	int shmid;
	volatile int * addr;
	pid_t  pid1;
	
	shmid=shmget(KEY1,4*1,SHM_R|SHM_W);
	addr=shmat(shmid,0,4);
	addr=0;
	pid1=fork();
	if(pid1==0)
	{
		addr[0]=1;
		sleep(1);
		addr=2;
		sleep(1);
		addr=3;
	}
	else
	{	
		printf("addr is %i \n",addr);
		sleep(1);
		printf("addr is %i \n",addr);
		sleep(1);
		printf("addr is %i \n",addr);
		sleep(1);

		
		if((shmctl(shmid,IPC_RMID, 0)) < 0) 
		{
			printf("shmctl shared mem delete NG\n");
			exit(1);
		} 				
		printf("shmctl shared mem delete OK\n"); 
	}

	return 0;
}

 

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NE_ADDR_RESOLVE(3)						neon API reference						NE_ADDR_RESOLVE(3)

NAME
ne_addr_resolve, ne_addr_result, ne_addr_first, ne_addr_next, ne_addr_error, ne_addr_destroy - functions to resolve hostnames to addresses SYNOPSIS
#include <ne_socket.h> ne_sock_addr *ne_addr_resolve(const char *hostname, int flags); int ne_addr_result(const ne_sock_addr *addr); const ne_inet_addr *ne_addr_first(ne_sock_addr *addr); const ne_inet_addr *ne_addr_next(ne_sock_addr *addr); char *ne_addr_error(const ne_sock_addr *addr, char *buffer, size_t bufsiz); void ne_addr_destroy(ne_sock_addr *addr); DESCRIPTION
The ne_addr_resolve function resolves the given hostname, returning an ne_sock_addr object representing the address (or addresses) associated with the hostname. The flags parameter is currently unused, and must be passed as 0. The hostname passed to ne_addr_resolve can be a DNS hostname (e.g. "www.example.com") or an IPv4 dotted quad (e.g. "192.0.34.72"); or, on systems which support IPv6, an IPv6 hex address, which may be enclosed in brackets, e.g. "[::1]". To determine whether the hostname was successfully resolved, the ne_addr_result function is used, which returns non-zero if an error occurred. If an error did occur, the ne_addr_error function can be used, which will copy the error string into a given buffer (of size bufsiz). The functions ne_addr_first and ne_addr_next are used to retrieve the Internet addresses associated with an address object which has been successfully resolved. ne_addr_first returns the first address; ne_addr_next returns the next address after the most recent call to ne_addr_next or ne_addr_first, or NULL if there are no more addresses. The ne_inet_addr pointer returned by these functions can be passed to ne_sock_connect to connect a socket. After the address object has been used, it should be destroyed using ne_addr_destroy. RETURN VALUE
ne_addr_resolve returns a pointer to an address object, and never NULL. ne_addr_error returns the buffer parameter . EXAMPLES
The code below prints out the set of addresses associated with the hostname www.google.com. ne_sock_addr *addr; char buf[256]; addr = ne_addr_resolve("www.google.com", 0); if (ne_addr_result(addr)) { printf("Could not resolve www.google.com: %s ", ne_addr_error(addr, buf, sizeof buf)); } else { const ne_inet_addr *ia; printf("www.google.com:"); for (ia = ne_addr_first(addr); ia != NULL; ia = ne_addr_next(addr)) { printf(" %s", ne_iaddr_print(ia, buf, sizeof buf)); } putchar(' '); } ne_addr_destroy(addr); SEE ALSO
ne_iaddr_print AUTHOR
Joe Orton <neon@lists.manyfish.co.uk> Author. COPYRIGHT
neon 0.29.6 3 May 2011 NE_ADDR_RESOLVE(3)
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