Linux-interprocess communication-shared memory

One, shared memory
Shared memory is the most efficient way to communicate, because there is no need for a process to be copied to the kernel and another process to read in the kernel.

Second, ipcs-m View shared memory
Ipcrm-m Deleting shared memory

Three, the main function
Shmget Create

Shmctl Delete

Shmat Hook up

SHMDT Cancel Hook up

Man function Name View * * * *
Iv. implementation of the Code
Comm.h

1 #pragma once    2 #include <stdio.h>    3 #include <stdlib.h>    4 #include <unistd.h>    5 # Include<sys/ipc.h>    6 #include <sys/shm.h>    7 #define _PATH_ "."    8 #define _PROJID_ 0x666    9 #define _SHM_SIZE_ 4096   int getshmget ();   one int destoryshm (int shm_id);   char* at_shm (int shm_id);   int Delete_shm (char *addr);

Comm.c

1 #include "comm.h"    2 int getshmget ()    3 {    4     key_t key=ftok (_path_,_projid_);    5     6     int shmflg=ipc_creat |0666;    7     int Shm_id=shmget (KEY,_SHM_SIZE_,SHMFLG);    8     if (shm_id<0)    9     {         perror ("Shmget");   One by one         return-1;   The     return shm_id;    destoryshm int (int shm_id) +   {     shmctl return (shm_id,ipc_rmid,null);    char* at_shm (int shm_id) (     char*) Shmat (shm_id,null,0);   Delete_shm Int (char *addr)-   {     shmdt return (addr);   28}

Client.c

1 #include "comm.h"    2 int main ()    3 {    4     int shm_id=getshmget ();    5     Char *addr=at_shm (shm_id);    6     int i=0;    7 for     (; i<_shm_size_;i++)    8     {    9         addr[i]= ' A ';   Ten         addr[i+1]= ' + ';         sleep (1);     delete_shm (addr);     return 0;   15}

Server.c

1 #include "comm.h"    2 int main ()    3 {    4     int shm_id=getshmget ();    5     char * ADDR=AT_SHM (shm_id);    6     int i=0;    7     for (; i<_shm_size_;i++)    8     {    9         printf ("%s\n", addr);   Ten         Sleep (1);   One     }     delete_shm (addr);     Destoryshm (shm_id);     return 0;   15}

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