mqtt客户端连接服务器的C语言代码实现

下面是基于MQTT C语言库的MQTT客户端连接服务器的代码实现：

1. 引入MQTT C语言库

#include "MQTTClient.h"

2. 定义MQTT客户端连接参数

MQTTClient client;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;

3. 初始化MQTT客户端连接参数

MQTTClient_create(&client, "tcp://localhost:1883", "MQTTClientC", MQTTCLIENT_PERSISTENCE_NONE, NULL);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;

4. 连接MQTT服务器

if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) {
    printf("Failed to connect, return code %d\n", rc);
    exit(-1);
}

5. 断开与MQTT服务器的连接

MQTTClient_disconnect(client, 10000);
MQTTClient_destroy(&client);

完整代码实现：

#include <stdio.h>
#include <stdlib.h>
#include "MQTTClient.h"

int main(int argc, char* argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    int rc;

    MQTTClient_create(&client, "tcp://localhost:1883", "MQTTClientC", MQTTCLIENT_PERSISTENCE_NONE, NULL);
    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;

    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) {
        printf("Failed to connect, return code %d\n", rc);
        exit(-1);
    }

    printf("MQTT client connected to server successfully!\n");

    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);

    return rc;
}