程序間通過共享記憶體來實作通信,完成父程序寫入記憶體,子程序從記憶體讀出并且把大寫轉換成小寫
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define BUFFER_SIZE 2048
void 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)//鐢寵鍐呭瓨
{
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));//鎷瘋礉鏁版嵁
strncpy(shm_addr,flag,strlen(flag));//鎷瘋礉鏍囧織
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)//鍒犻櫎鐢寵鐨勫唴瀛? {
perror("shmctl:IPC_RMID");
exit(1);
}
else
printf("delete shared memory\n");
printf("finished!\n");
}
return 0;
}