Categories: Open C | Code Examples

This page was last modified 05:51, 1 October 2007.

From Forum Nokia Wiki

Shared Memory Description

Example Code is as follows(code follows the steps described in the above link):

#include <sys/shm.h>
#include <string.h>
#include <pthread.h>
 
pthread_t threadid;
#define SHM_KEY 1000
 
void* ShmReadThread(void* arg)
{
   int shmid = shmget(SHM_KEY, 1024, IPC_CREAT);
   char* ch = (char*)shmat(shmid, 0, 0);
   char name[10];
   strncpy(name, ch, 3);
   // name contained "abc"
   shmdt(ch);
   return 0;
}
 
void CreateThreadL()
   {
   pthread_create(&threadid,(pthread_attr_t *)NULL,ShmReadThread, NULL);
   }
 
int main()
{
   char* ch;
   int shmid = shmget(SHM_KEY, 1024, IPC_CREAT);
   int threadRetVal = 0;
   if( shmid == -1)
       return -1;
   ch = (char*)shmat(shmid, 0, 0);
   if((int)ch == -1)
   {
       shmctl(shmid, IPC_RMID, NULL);
       return -1;
   }
   strcpy(ch, "abc");
   CreateThreadL();
   
   pthread_join(threadid, (void**)threadRetVal);
   shmdt(ch);
   shmctl(shmid, IPC_RMID, NULL);
   return 0;
}

Links

• Shared Memory
• How_to_communicate_between_two_threads_or_processes