Linux下的C语言编程——进程间通信——内存共享

来源：互联网发布：网络招聘网编辑：程序博客网时间：2024/04/28 08:20

进程间通过共享内存来实现通信，完成父进程写入内存，子进程从内存读出并且把大写转换成小写

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/types.h>#include <sys/ipc.h>#include <sys/shm.h>#define BUFFER_SIZE 2048void strupr(char *str){char *p;p = str;while(*p != '\0'){if(*p >= 'A' && *p <= 'Z'){*p = *p + 32;}p++;}}int main(){    pid_t pid;    int shmid;    char *shm_addr;    char flag[]="parent";    char buff[BUFFER_SIZE];        if((shmid = shmget(IPC_PRIVATE,BUFFER_SIZE,0666)) < 0)// ask for memery    {       perror("shmget");       exit(1);    }    else        printf("create share memory!\n");        if((pid = fork()) < 0 )    {        perror("fork");        exit(1);    }    else if(pid == 0)//in son process    {        if((shm_addr = shmat(shmid,0,0)) == (void *)-1)//鏄犲皠        {            perror("child:shmat\n");            exit(1);        }        else             printf("child:Attach shared memory:%p\n",shm_addr);        while(strncmp(shm_addr,flag,strlen(flag)))//鍏堝皢鏍囧織鎷峰叆鍐呭瓨        {            printf("child: waiting for data...\n");            sleep(3);        }        strcpy(buff,shm_addr + strlen(flag));//鎷峰叆鍐呭瓨涓殑鏁版嵁strupr(buff);        printf("child:shared memory:%s\n",buff);                if(shmdt(shm_addr) < 0)//瑙ｉ櫎鏄犲皠        {            perror("child:shmdt");            exit(1);        }        else            printf("child:detached shared memory\n");    }    else    {        sleep(1);        if((shm_addr = shmat(shmid,(void *)0,0)) == (void *)-1)//鐢宠鍐呭瓨        {            perror("parent:shmat\n");            exit(1);        }        else        {            printf("parent attach share memory:%p\n",shm_addr);        }                sleep(1);        printf("input string:\n");                    fgets(buff,BUFFER_SIZE-strlen(flag),stdin);//杈撳叆鏁版嵁         strncpy(shm_addr+strlen(flag),buff,strlen(buff));//鎷疯礉鏁版嵁        strncpy(shm_addr,flag,strlen(flag));//鎷疯礉鏍囧織                 if(shmdt(shm_addr) < 0)//瑙ｉ櫎鏄犲皠        {             perror("parent:shmdt");             exit(1);        }        else            printf("parent: deattach shared memory\n");                    waitpid(pid,NULL,0);//绛夊緟瀛愯繘绋嬬粨鏉?                if(shmctl(shmid,IPC_RMID,NULL) == -1)//鍒犻櫎鐢宠鐨勫唴瀛?        {            perror("shmctl:IPC_RMID");            exit(1);        }        else            printf("delete shared memory\n");                 printf("finished!\n");    }    return 0;}

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