软讯网络 > 编程语言 > C/C++ > 一个自写的共享内存简单的例子，学习原理之用
【标 题】：一个自写的共享内存简单的例子，学习原理之用
【关键字】：
【来 源】：http://blog.csdn.net/yhniejun/archive/2007/01/23/1491124.aspx
一个自写的共享内存简单的例子，学习原理之用
/**//*
* shm_test.c
* 共享内存测试程序，往一个共享内存里循环写入数据
*/
#include <sys/shm.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#define SHARED_MEME "/tmp/share"
#define SHM_MODE 0600
#include <stdlib.h>
int main(void)
...{
key_t key;
long shm_id;
int i = 0, j;
char *ptr;
char *back;
char name[7] = "Ken Jun";
struct shmid_ds buff;
if ((key = ftok(SHARED_MEME, 0)) == -1)
printf("ftok error! ");
shm_id = shmget(key, 512, SHM_MODE | IPC_CREAT);
ptr = shmat(shm_id, 0, 0);
shmctl(shm_id, IPC_STAT, &buff);
back = ptr;
//for (i = 0; i < buff.shm_segsz; i++)
while(1)
...{
if (i >= (int)buff.shm_segsz / 7) ...{
ptr = back;
i = 0;
continue;
}
printf("在%p内存里", ptr);
printf("写入字段%d : ", i);
for (j = 0; j < 7; j++)
...{
*ptr = name[j];
printf("%c", *ptr);
ptr++;
}
printf(" . ");
usleep(5000);
i++;
}
shmdt(&shm_id);
shmctl(shm_id, IPC_RMID, NULL);
return 0;
}
/**//*
* shm_test_read.c
* 共享内存测试程序，从一个共享内存里循环读出数据
*/
#include <sys/shm.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#define SHARED_MEME "/tmp/share"
#define SHM_MODE 0600
int main(void)
...{
key_t key;
long shm_id;
int i = 0, j;
char *ptr;
char name[7];
char *back;
struct shmid_ds buff;
if ((key = ftok(SHARED_MEME, 0)) == -1)
printf("ftok error! ");
shm_id = shmget(key, 512, SHM_MODE | IPC_CREAT);
ptr = shmat(shm_id, 0, 0);
shmctl(shm_id, IPC_STAT, &buff);
back = ptr;
//for (i = 0; i < buff.shm_segsz; i++)
while(1)
...{
if (i >= (int)buff.shm_segsz / 7) ...{
ptr = back;
i = 0;
continue;
}
printf("从%p内存里", ptr);
printf("读出字段%d : ", i);
for (j = 0; j < 7; j++)
...{
printf("%c", *ptr);
ptr++;
}
printf(" . ");
usleep(5000);
i++;
}
shmdt(&shm_id);
return 0;
}
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