为什么msgrcv(）将垃圾字符馈送到缓冲区

现在，我正在尝试输出buf.mtext的内容，以便在继续我的程序之前确保输入正确。除了一件事外，一切似乎都很好；msgrcv((将垃圾字符放入缓冲区，接收进程输出垃圾字符。

这是我的发件人流程：

int main (void)
{
int  i;                 // loop counter
int  status_01;         // result status
int  msqid_01;          // message queue ID (#1)
key_t msgkey_01;        // message-queue key (#1)
unsigned int rand_num;
float temp_rand;
unsigned char eight_bit_num;
unsigned char counter = 0;
unsigned char even_counter = 0;
unsigned char odd_counter = 0;
srand(time(0));
struct message {
long mtype;
char mtext[BUFFER_SIZE];
} buf_01;
msgkey_01 = MSG_key_01; // defined at top of file
msqid_01 = msgget(msgkey_01, 0666 | IPC_CREAT)
if ((msqid_01 <= -1) { exit(1); }
/* wait for a key stroke at the keyboard ---- */
eight_bit_num = getchar();
buf_01.mtype = 1;
/* send one eight-bit number, one at a time  ------------ */
for (i = 0; i < NUM_REPEATS; i++)
{
temp_rand = ((float)rand()/(float)RAND_MAX)*255.0;
rand_num = (int)temp_rand;
eight_bit_num = (unsigned char)rand_num;
if ((eight_bit_num % 2) == 0)
{
printf("Even number: %dn", eight_bit_num);
even_counter = even_counter + eight_bit_num;
}
else
{
printf("Odd number:       %dn", eight_bit_num);
odd_counter = odd_counter + eight_bit_num;
}
/* update the counters ------------------------------ */
counter = counter + eight_bit_num;
if((eight_bit_num % 2) == 0) { even_counter = even_counter + eight_bit_num; }
else { odd_counter = odd_counter + eight_bit_num; }
buf_01.mtext[0] = eight_bit_num;   // copy the 8-bit number
buf_01.mtext[1] = '';            // null-terminate it
status_01 = msgsnd(msqid_01, (struct msgbuf *)&buf_01, sizeof(buf_01.mtext), 0);
status_01 = msgctl(msqid_01, IPC_RMID, NULL);
}

这是我的接收器过程：

int main() {
struct message {
long mtype;
char mtext[BUFFER_SIZE];
} buf;
int msqid;
key_t msgkey;
msgkey = MSG_key_01;
msqid = msgget(msgkey, 0666); // connect to message queue
if (msqid < 0) {
printf("Failedn");
exit(1);
}
else {
printf("Connectedn");
}
if (msgrcv(msqid, &buf, BUFFER_SIZE, 0, 0) < 0) { // read message into buf
perror("msgrcv");
exit(1);
}
printf("Data received is: %s n", buf.mtext);
printf("Done receiving messages.n");
return 0;
}

输出通常如下所示：

Data received is: ▒
Done receiving messages.

我已经确保每次运行发送方和接收方进程后都清除我的消息队列，因为我发现这可能会导致问题。提前感谢您的帮助。