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error LNK2019: 无法解析的外部符号 _MQTTClient_create

extern "C"{
#include <MQTTClient.h>
#include <MQTTClientPersistence.h>
}#pragma comment(lib, "paho-mqtt3a.lib")
1>MQTT.obj : error LNK2019: 无法解析的外部符号 _MQTTClient_create,该符号在函数 "public: bool __thiscall CMQTTHelper::connectServer(void)" (?connectServer@CMQTTHelper@@QAE_NXZ) 中被引用
1>MQTT.obj : error LNK2019: 无法解析的外部符号 _MQTTClient_disconnect,该符号在函数 "public: bool __thiscall CMQTTHelper::connectServer(void)" (?connectServer@CMQTTHelper@@QAE_NXZ) 中被引用
1>MQTT.obj : error LNK2019: 无法解析的外部符号 _MQTTClient_destroy,该符号在函数 "public: bool __thiscall CMQTTHelper::connectServer(void)" (?connectServer@CMQTTHelper@@QAE_NXZ) 中被引用

原因:

1、paho-mqtt3a : a表示的是异步消息推送(asynchronous),对应接口 MQTTAsync_

2、paho-mqtt3c : c 表示的应该是同步(Synchronize)对应接口 MQTTClient_

解决方法:

extern "C"{
#include <MQTTAsync.h> // 包含异步头
#include <MQTTClientPersistence.h>
}

接口全部使用异步接口

MQTTAsync mMQTTClient;

if (mMQTTClient != NULL)
{
MQTTAsync_disconnectOptions opts = MQTTAsync_disconnectOptions_initializer;
opts.onSuccess = NULL;
opts.context = this;
MQTTAsync_disconnect(mMQTTClient, &opts);
MQTTAsync_destroy(&mMQTTClient);
mMQTTClient = NULL;
}

MQTTAsync_create(&mMQTTClient, mSvrAddr.c_str(), mClientId.c_str(), MQTTCLIENT_PERSISTENCE_NONE, NULL);
MQTTAsync_connectOptions connOpts = MQTTAsync_connectOptions_initializer;
connOpts.keepAliveInterval = 5;
connOpts.cleansession = 1;

 

 

 

 

 

 

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