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进程间通信——共享内存（Shared Memory）_ypt-CSDN博客_共享内存

例程

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//comm.h
#ifndef _COMM_H__
#define _COMM_H__
 
#include<stdio.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
 
#define PATHNAME "."
#define PROJ_ID 0x6666
 
int CreateShm(int size);
int DestroyShm(int shmid);
int GetShm(int size);
#endif
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//comm.c
#include"comm.h"
 
static int CommShm(int size,int flags)
{
	key_t key = ftok(PATHNAME,PROJ_ID);
	if(key < 0)
	{
		perror("ftok");
		return -1;
	}
	int shmid = 0;
	if((shmid = shmget(key,size,flags)) < 0)
	{
		perror("shmget");
		return -2;
	}
	return shmid;
}
int DestroyShm(int shmid)
{
	if(shmctl(shmid,IPC_RMID,NULL) < 0)
	{
		perror("shmctl");
		return -1;
	}
	return 0;
}
int CreateShm(int size)
{
	return CommShm(size,IPC_CREAT | IPC_EXCL | 0666);
}
int GetShm(int size)
{
	return CommShm(size,IPC_CREAT);
}
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//client.c
#include"comm.h"
 
int main()
{
	// 获得共享内存的id
	int shmid = GetShm(4096);
	sleep(1);
	// 将共享内存映射到本进程的地址空间
	char *addr = shmat(shmid,NULL,0);
	sleep(2);
	int i = 0;
	while(i < 26)
	{
		addr[i] = 'A' + i;
		i++;
		addr[i] = 0;
		sleep(1);
	}
	// 将共享内存从本进程的地址空间中卸载
	shmdt(addr);
	sleep(2);
	return 0;
}
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//server.c
#include"comm.h"
 
int main()
{
	// 创建并获得共享内存的id
	int shmid = CreateShm(4096);
	// 将共享内存映射到本进程的地址空间
	char *addr = shmat(shmid,NULL,0);
	sleep(2);
	int i = 0;
	while(i++ < 26)
	{
		printf("client# %s\n",addr);
		sleep(1);
	}
	// 将共享内存从本进程的地址空间中卸载
	shmdt(addr);
	sleep(2);
	// 删除共享内存
	DestroyShm(shmid);
	return 0;
}
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//Makefile
.PHONY:all
all:server client
 
client:client.c comm.c
	gcc -o $@ $^
server:server.c comm.c
	gcc -o $@ $^
 
.PHONY:clean
clean:
	rm -f client server