编写一对程序send.c和recv.c，前者负责创建消息队列并发送消息（由用户输入消息），后者负责接收并打印出消息，当接收数据为“end”时结束，由后者删除该消息队列。

send.c代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/msg.h>

#define MAX_MSG_SIZE 1024

typedef struct {
    long msg_type;
    char msg_text[MAX_MSG_SIZE];
} Message;

int main() {
    key_t key = ftok(".", 'a');
    int msgid = msgget(key, IPC_CREAT | 0666);

    if (msgid == -1) {
        perror("msgget failed!");
        exit(EXIT_FAILURE);
    }

    Message message;

    while (1) {
        printf("Enter message: ");
        fgets(message.msg_text, MAX_MSG_SIZE, stdin);

        // Remove trailing newline character
        size_t len = strlen(message.msg_text);
        if (message.msg_text[len - 1] == '\n') {
            message.msg_text[len - 1] = '\0';
        }

        if (strcmp(message.msg_text, "end") == 0) {
            break;
        }

        message.msg_type = 1;

        if (msgsnd(msgid, &message, MAX_MSG_SIZE, 0) == -1) {
            perror("msgsnd failed!");
            exit(EXIT_FAILURE);
        }
    }

    if (msgctl(msgid, IPC_RMID, NULL) == -1) {
        perror("msgctl(IPC_RMID) failed!");
        exit(EXIT_FAILURE);
    }

    return 0;
}

recv.c代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/msg.h>

#define MAX_MSG_SIZE 1024

typedef struct {
    long msg_type;
    char msg_text[MAX_MSG_SIZE];
} Message;

int main() {
    key_t key = ftok(".", 'a');
    int msgid = msgget(key, 0666);

    if (msgid == -1) {
        perror("msgget failed!");
        exit(EXIT_FAILURE);
    }

    Message message;

    while (1) {
        if (msgrcv(msgid, &message, MAX_MSG_SIZE, 0, 0) == -1) {
            perror("msgrcv failed!");
            exit(EXIT_FAILURE);
        }

        printf("Received message: %s\n", message.msg_text);

        if (strcmp(message.msg_text, "end") == 0) {
            break;
        }
    }

    if (msgctl(msgid, IPC_RMID, NULL) == -1) {
        perror("msgctl(IPC_RMID) failed!");
        exit(EXIT_FAILURE);
    }

    return 0;
}