share memory demo

shm.h

 1 #ifndef __SHM_H
 2 #define __SHM_H
 3 
 4 #include <stdio.h>
 5 
 6 #include <sys/ipc.h>
 7 #include <sys/shm.h>
 8 
 9 #define SHM_KEY     ((key_t)0x20201231)
10 #define SHM_SIZE    (16 * 1024 * 1024)
11 
12 #endif//__SHM_H

 

shm_A.c

 1 #include "shm.h"
 2 
 3 #include <string.h>
 4 
 5 
 6 int main(void)
 7 {
 8     int shmid = shmget(SHM_KEY,SHM_SIZE,IPC_CREAT|0664);
 9     if(-1 == shmid)
10     {
11         printf("shmget fail\n");
12         return -1;
13     }
14     else
15     {
16         printf("shmget ok,shmid = %d\n",shmid);
17     }
18 
19     void* ptr = shmat(shmid,NULL,0);
20     if(((void*)-1) == ptr)
21     {
22         printf("shmat fail\n");
23         return -1;
24     }
25     else
26     {
27         printf("shmat ok,ptr = %p\n",ptr);
28     }
29 
30     char tmpString[] = "hello ipc shm!";
31     memcpy(ptr,tmpString,sizeof(tmpString));
32 
33     getchar();
34 
35     return 0;
36 }

 

shm_B.c

 1 #include "shm.h"
 2 
 3 int main(void)
 4 {
 5     int shmid = shmget(SHM_KEY,SHM_SIZE,IPC_CREAT|0664);
 6     if(-1 == shmid)
 7     {
 8         printf("shmget fail\n");
 9         return -1;
10     }
11     else
12     {
13         printf("shmget ok,shmid = %d\n",shmid);
14     }
15 
16     void* ptr = shmat(shmid,NULL,0);
17     if(((void*)-1) == ptr)
18     {
19         printf("shmat fail\n");
20         return -1;
21     }
22     else
23     {
24         printf("shmat ok,ptr = %p\n",ptr);
25     }
26 
27     printf("%s\n",(char*)ptr);
28 
29     getchar();
30 
31     return 0;
32 }

 

1.the 1st var of shmget can be get from ftok

2.you can check the share memory status by cmd

　　ipcs -m

3.you can delete the share memory by cmd

　　ipcrm -M key

or　ipcrm -m shmid

标签：shmget,demo,memory,share,SHM,printf,shmid,include,ptr
来源： https://www.cnblogs.com/lanmufan/p/14218611.html