一 **
#include #include #include #include #include "stdio.h"
#include "errno.h"
void msg_stat(int,struct msqid_ds );
main()
msg_sbuf;
struct msgmbuf
msg_rbuf;
struct msqid_ds msg_ginfo;
char msgpath="./test";
key=ftok(msgpath,'b');
gflags=ipc_creat|ipc_excl;
msgid=msgget(key,gflags|00666);
if(msgid==-1)
//建立乙個訊息佇列後，輸出訊息佇列預設屬性
msg_stat(msgid,msg_ginfo);
sflags=ipc_nowait;
msg_sbuf.mtype=10;
msg_sbuf.mtext[0]='a';
reval=msgsnd(msgid,&msg_sbuf,sizeof(msg_sbuf.mtext),sflags);
if(reval==-1)
//傳送乙個訊息後，輸出訊息佇列屬性
msg_stat(msgid,msg_ginfo);
reval=msgctl(msgid,ipc_rmid,null);//刪除訊息佇列
if(reval==-1)
}void msg_stat(int msgid,struct msqid_ds msg_info)
printf("\n");
printf("current number of bytes on queue is %d\n",msg_info.msg_cbytes);
printf("number of messages in queue is %d\n",msg_info.msg_qnum);
printf("max number of bytes on queue is %d\n",msg_info.msg_qbytes);
//每個訊息佇列的容量（位元組數）都有限制msgmnb，值的大小因系統而異。在建立新的訊息佇列時，//msg_qbytes的預設值就是msgmnb
printf("pid of last msgsnd is %d\n",msg_info.msg_lspid);
printf("pid of last msgrcv is %d\n",msg_info.msg_lrpid);
printf("last msgsnd time is %s", ctime(&(msg_info.msg_stime)));
printf("last msgrcv time is %s", ctime(&(msg_info.msg_rtime)));
printf("last change time is %s", ctime(&(msg_info.msg_ctime)));
printf("msg uid is %d\n",msg_info.msg_perm.uid);
printf("msg gid is %d\n",msg_info.msg_perm.gid);
}
[root@localhost test]# g++ test.cpp -o test
[root@localhost test]# ./test
current number of bytes on queue is 0
number of messages in queue is 0
max number of bytes on queue is 16384
pid of last msgsnd is 0
pid of last msgrcv is 0
last msgsnd time is thu jan 1 08:00:00 1970
last msgrcv time is thu jan 1 08:00:00 1970
last change time is fri apr 5 19:11:13 2019
msg uid is 0
msg gid is 0
current number of bytes on queue is 1
number of messages in queue is 1
max number of bytes on queue is 16384
pid of last msgsnd is 1055
pid of last msgrcv is 0
last msgsnd time is fri apr 5 19:11:15 2019
last msgrcv time is thu jan 1 08:00:00 1970
last change time is fri apr 5 19:11:13 2019
msg uid is 0
msg gid is 0
可以看到，剛開始時，訊息佇列的訊息是0，傳送乙個後，佇列裡面的訊息個數就變成1了。因為我們傳送的訊息是字元「a」，長度是1，所以訊息佇列的長度就是乙個位元組。
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