方法一：
消息队列的接口
#include "fcntl.h"
#include "sys/stat.h"
#include "mqueue.h"// 创建消息队列实例。name: 消息队列名称。成功返回0，失败返回-1，错误码存于error中
mqd_t mq_open(const char *name, int oflag, mode_t mode, struct mq_attr *attr);// 无限阻塞方式接收消息。成功返回0，失败返回-1
mqd_t mq_receive(mqd_t mqdes, char *msg_ptr, size_t msg_len, unsigned *msg_prio);// 指定超时时间阻塞方式接收消息。成功返回0，失败返回-1
mqd_t mq_timedreceive(mqd_t mqdes, char *msg_ptr, size_t msg_len, unsigned *msg_prio, const struct timespec *abs_timeout);// 无限阻塞方式发送消息。成功返回0，失败返回-1
mqd_t mq_send(mqd_t mqdes, const char *msg_ptr, size_t msg_len, unsigned msg_prio);// 指定超时时间阻塞方式发送消息。成功返回0，失败返回-1
mqd_t mq_timedsend(mqd_t mqdes, const char *msg_ptr, size_t msg_len, unsigned msg_prio, const struct timespec *abs_timeout);// 关闭消息队列。 成功返回0，失败返回-1
mqd_t mq_close(mqd_t mqdes);// 分离消息队列。 成功返回0，失败返回-1
mqd_t mq_unlink(const char *name);sender.cpp
#include <fcntl.h> // For O_* constants
#include <mqueue.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h> // For mode constants
#include <unistd.h>#define MQ_MSG_MAX_SIZE 512 // 最大消息长度
#define MQ_MSG_MAX_ITEM 5 // 最大消息数目static mqd_t s_mq;typedef struct _msg_data
{char buf[128];int num;
}msg_data_t;void send_data(void)
{static int num = 0;msg_data_t send_data = {0};++num;strcpy(send_data.buf, "Hello Randy");send_data.num = num;int ret = mq_send(s_mq, (char*)&send_data, sizeof(send_data), 0);if (ret < 0){perror("mq_send error");return;}printf("send msg = %s, num = %d\n", send_data.buf, send_data.num);
}int main(void) {int ret = 0;struct mq_attr attr;// 创建消息队列memset(&attr, 0, sizeof(attr));attr.mq_maxmsg = MQ_MSG_MAX_ITEM;attr.mq_msgsize = MQ_MSG_MAX_SIZE;attr.mq_flags = 0;s_mq = mq_open("/randy1", O_CREAT | O_RDWR, 0777, &attr);if (-1 == s_mq) {perror("mq_open error");return -1;}for (size_t i = 0; i < 10; i++) {send_data();sleep(1);}mq_close(s_mq);return 0;
}
receiver.cpp
#include <fcntl.h> // For O_* constants
#include <mqueue.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h> // For mode constants
#include <unistd.h>#define MQ_MSG_MAX_SIZE 512 // 最大消息长度
#define MQ_MSG_MAX_ITEM 5 // 最大消息数目static mqd_t s_mq;typedef struct _msg_data
{char buf[128];int num;
}msg_data_t;void receive_data(void)
{static int num = 0;msg_data_t receive_data = {0};int ret = mq_receive(s_mq, (char*)&receive_data, MQ_MSG_MAX_SIZE, 0);if (ret < 0){perror("mq_send error");return;}printf("send msg = %s, num = %d\n", receive_data.buf, receive_data.num);
}int main(void) {int ret = 0;struct mq_attr attr;// 创建消息队列memset(&attr, 0, sizeof(attr));attr.mq_maxmsg = MQ_MSG_MAX_ITEM;attr.mq_msgsize = MQ_MSG_MAX_SIZE;attr.mq_flags = 0;s_mq = mq_open("/randy1", O_RDWR, 0777, &attr);if (-1 == s_mq) {perror("mq_open error");return -1;}for (size_t i = 0; i < 10; i++) {receive_data();sleep(1);}mq_close(s_mq);return 0;
}
注意⚠️ man 3 mq_receive 可以知道，接受指定的 msg_len 必须大于等于 attr 中的mq_msgsize；同理，发送时，必须小于attr指定的mq_msgsize
方法二
#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
#include <cstdio>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <cstring>struct my_msg_st { long int my_msg_type; char text[100];
};int send_msg(int msqid, const std::string &text) { my_msg_st msg; msg.my_msg_type = 1; // 消息类型 strncpy(msg.text, text.c_str(), sizeof(msg.text)); // 复制文本到消息结构体 if (msgsnd(msqid, &msg, sizeof(msg), 0) == -1) { // 发送消息 perror("msgsnd"); return -1; } return 0;
}int receive_msg(int msqid) { my_msg_st msg; if (msgrcv(msqid, &msg, sizeof(msg), 1, 0) == -1) { // 接收消息 perror("msgrcv"); return -1; } std::cout << "Received: " << msg.text << std::endl; // 打印接收到的消息 return 0;
}int main() { int msqid; key_t key = ftok("/tmp", 'R'); // 使用文件系统路径作为关键字，创建唯一的键值 if ((msqid = msgget(key, IPC_CREAT | 0666)) == -1) { // 创建消息队列 perror("msgget"); return -1; } std::cout << "Message queue created with id: " << msqid << std::endl; send_msg(msqid, "Hello, World!"); // 发送消息 receive_msg(msqid); // 接收消息 return 0;
}
