1、代码

#include <stdio.h>
#include <mosquitto.h>

void my_message_callback(struct mosquitto *mosq, void *userdata, const struct mosquitto_message *message)
{
	if(message->payloadlen){
		printf("%s %s\n", message->topic, message->payload);
	}else{
		printf("%s (null)\n", message->topic);
	}
	fflush(stdout);
}

void my_connect_callback(struct mosquitto *mosq, void *userdata, int result)
{
	int i;
	if(!result){
		/* Subscribe to broker information topics on successful connect. */
		mosquitto_subscribe(mosq, NULL, "$SYS/#", 2);
	}else{
		fprintf(stderr, "Connect failed\n");
	}
}

void my_subscribe_callback(struct mosquitto *mosq, void *userdata, int mid, int qos_count, const int *granted_qos)
{
	int i;

	printf("Subscribed (mid: %d): %d", mid, granted_qos[0]);
	for(i=1; i<qos_count; i++){
		printf(", %d", granted_qos[i]);
	}
	printf("\n");
}

void my_log_callback(struct mosquitto *mosq, void *userdata, int level, const char *str)
{
	/* Pring all log messages regardless of level. */
	printf("%s\n", str);
}

int main(int argc, char *argv[])
{
	int i;
	char *host = "192.168.xx.xx";
	int port = 1883;
	int keepalive = 60;
	bool clean_session = true;
	struct mosquitto *mosq = NULL;

	mosquitto_lib_init();
	mosq = mosquitto_new(NULL, clean_session, NULL);
	if(!mosq){
		fprintf(stderr, "Error: Out of memory.\n");
		return 1;
	}
	mosquitto_log_callback_set(mosq, my_log_callback);
	mosquitto_connect_callback_set(mosq, my_connect_callback);
	mosquitto_message_callback_set(mosq, my_message_callback);
	mosquitto_subscribe_callback_set(mosq, my_subscribe_callback);

	if(mosquitto_connect(mosq, host, port, keepalive)){
		fprintf(stderr, "Unable to connect.\n");
		return 1;
	}

	mosquitto_loop_forever(mosq, -1, 1);

	mosquitto_destroy(mosq);
	mosquitto_lib_cleanup();
	return 0;
}

2、库目录结构

3、编译
g++ ./testmosqutto.cpp -I ./include -L ./lib -lmosquitto
4、ldd a.out提示找不到mosquitto库
5、 sudo cp ./lib/libmosquitto.so /usr/lib/libmosquitto.so.1
6、从新ldd

7、执行

8、mosquitto_new第一个参数如果指定名称，那么就使用指定名称，否则会自动生成clientid.