linux c之shm共享内存的使用例子

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//shm_test.c#include <sys/shm.h>#include <stdio.h>#include <stdlib.h>#define BUFFERSIZE 1024int main(int argc, char const *argv[]){int shmid;char* shmadd;//创建一个共享内存对象if((shmid=shmget(IPC_PRIVATE,BUFFERSIZE,0666))<0){perror("shmget error");exit(-1);}else{printf("create shared memory:%d\n",shmid);}system("ipcs -m");//挂载共享内存到进程中if((shmadd=shmat(shmid,0,0))<(char*)0){perror("shmat error");exit(-1);}else{printf("attached shared memory\n");}system("ipcs -m");//卸载共享内存if(shmdt(shmadd)<0){perror("shmdt error");exit(-1);}else{printf("deleted shared memory\n");}system("ipcs -m");//完成对共享内存的控制,释放共享内存//IPC_RMID：删除这片共享内存if(shmctl(shmid,IPC_RMID,0)<0){perror("shmctl error");exit(-1);}printf("release shared memory\n");exit(0);return 0;}

//shm_server.c#include <stdio.h>#include <stdlib.h>#include <string.h>#include <fcntl.h>#include <sys/ipc.h>//ipc#include <sys/shm.h>#include <unistd.h>struct sys_data{float data_rh;float data_t;};//基于课程http://edu.51cto.com/lesson/id-131448.html//linux c之shm共享内存的使用例子int main(int argc, char const *argv[]){void* shm=(void*)0;int shmid;struct sys_data *da;float ftemp=0.0,fhumi=0.0;//set share memory;//linxu可以使用ipcrm -m shmid 删除此共享内存。//创建一个共享内存对象shmid=shmget((key_t)8891,sizeof(struct sys_data),0666|IPC_CREAT);if(shmid==-1){printf("shmget error\n");exit(-1);}else{printf("server shmid=%d\n", shmid);}//把共享内存映射到调用进程的地址空间//挂载共享内存到进程中shm=shmat(shmid,(void*)0,0);if(shm==(void*)(-1)){printf("shmat error\n");exit(-1);}da=shm;printf("shmat start\n");while(1){ftemp=rand()%100;fhumi=rand()%100;da->data_t=ftemp;da->data_rh=fhumi;sleep(1);}return 0;}

//shm_client.c#include <stdio.h>#include <stdlib.h>#include <string.h>#include <fcntl.h>#include <sys/ipc.h>//ipc#include <sys/shm.h>#include <unistd.h>struct sys_data{float data_rh;float data_t;};int main(int argc, char const *argv[]){void* shm=(void*)0;int shmid;struct sys_data *da;float ftemp=0.0,fhumi=0.0;//set share memory;//创建一个共享内存对象shmid=shmget((key_t)8891,sizeof(struct sys_data),0666|IPC_CREAT);if(shmid==-1){printf("shmget error\n");exit(-1);}else{printf("client shmid=%d\n", shmid);}//挂载共享内存到进程中shm=shmat(shmid,(void*)0,0);if(shm==(void*)(-1)){printf("shmat error\n");exit(-1);}da=shm;while(1){sleep(2);printf("temp=%.1f,humi=%.1f\n",da->data_t,da->data_rh );}return 0;}

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