如何安装 Eclipse Paho C
How to install Eclipse Paho C
我正在尝试 运行 在 Eclipse 中使用 Eclipse Paho C 的简单客户端程序。
我做了以下事情：
1) 创建新项目
2) 复制"include"文件夹和"lib"文件夹到项目目录
3) 添加"include" 文件夹目录到包含路径
4) Link 如下图所示带有链接器的库
然而，当我构建以下代码时：
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "MQTTClient.h"
#define ADDRESS "tcp://localhost:1883"
#define CLIENTID "ExampleClientPub"
#define TOPIC "MQTT Examples"
#define PAYLOAD "Hello World!"
#define QOS 1
#define TIMEOUT 10000L
int main(int argc, char* argv[])
{
MQTTClient client;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
MQTTClient_message pubmsg = MQTTClient_message_initializer;
MQTTClient_deliveryToken token;
int rc;
MQTTClient_create(&client, ADDRESS, CLIENTID,
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);
}
pubmsg.payload = PAYLOAD;
pubmsg.payloadlen = strlen(PAYLOAD);
pubmsg.qos = QOS;
pubmsg.retained = 0;
MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);
printf("Waiting for up to %d seconds for publication of %s\n"
"on topic %s for client with ClientID: %s\n",
(int)(TIMEOUT/1000), PAYLOAD, TOPIC, CLIENTID);
rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
printf("Message with delivery token %d delivered\n", token);
MQTTClient_disconnect(client, 10000);
MQTTClient_destroy(&client);
return rc;
}
我得到以下信息：
19:31:16 **** Rebuild of configuration Debug for project MQTT_C_Client ****
Info: Internal Builder is used for build
gcc "-IE:\WS\MQTT_C_Client\includes" -O0 -g3 -Wall -c -fmessage-length=0 -o "src\main.o" "..\src\main.c"
gcc "-LE:\WS\MQTT_C_Client\libs" -o MQTT_C_Client.exe "src\main.o" -lpaho-mqtt3a -lpaho-mqtt3as -lpaho-mqtt3c -lpaho-mqtt3cs
src\main.o: In function `main':
E:\WS\MQTT_C_Client\Debug/../src/main.c:29: undefined reference to `MQTTClient_create'
E:\WS\MQTT_C_Client\Debug/../src/main.c:34: undefined reference to `MQTTClient_connect'
E:\WS\MQTT_C_Client\Debug/../src/main.c:43: undefined reference to `MQTTClient_publishMessage'
E:\WS\MQTT_C_Client\Debug/../src/main.c:47: undefined reference to `MQTTClient_waitForCompletion'
E:\WS\MQTT_C_Client\Debug/../src/main.c:49: undefined reference to `MQTTClient_disconnect'
E:\WS\MQTT_C_Client\Debug/../src/main.c:50: undefined reference to `MQTTClient_destroy'
collect2.exe: error: ld returned 1 exit status
19:31:29 Build Finished (took 12s.643ms)
知道我错过了什么吗？
这是一个可能的错误原因。 （可能不是正确的解决方案，具体取决于底层链接器）
是-L相对于-l的位置给你带来了麻烦（我的观察有点粗心）。来自 gcc 联机帮助页：
You can mix options and other arguments. For the most part, the order you use doesn't matter. Order does matter when you
use several options of the same kind; for example, if you specify -L more than once, the directories are searched in the
order specified. Also, the placement of the -l option is significant.
这可能会有所不同，具体取决于底层链接器 -L 库搜索的范围。尝试确保 -L 和 -l 彼此相邻，没有任何其他直接链接的对象路径将它们分开。
例如，
gcc -o myprog main.o foo.o bar.o -L/some/path -L/some/other/path -la -lb
还可以
然而，
gcc -o myprog main.o -L/some/path foo.o bar.o -L/some/other/path -la -lb
不是。
我通过使用 Cygwin 在 Windows 上构建库并使用生成的库解决了这个问题。
我正在尝试 运行 在 Eclipse 中使用 Eclipse Paho C 的简单客户端程序。
我做了以下事情：
1) 创建新项目
2) 复制"include"文件夹和"lib"文件夹到项目目录
3) 添加"include" 文件夹目录到包含路径
4) Link 如下图所示带有链接器的库
然而，当我构建以下代码时：
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "MQTTClient.h"
#define ADDRESS "tcp://localhost:1883"
#define CLIENTID "ExampleClientPub"
#define TOPIC "MQTT Examples"
#define PAYLOAD "Hello World!"
#define QOS 1
#define TIMEOUT 10000L
int main(int argc, char* argv[])
{
MQTTClient client;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
MQTTClient_message pubmsg = MQTTClient_message_initializer;
MQTTClient_deliveryToken token;
int rc;
MQTTClient_create(&client, ADDRESS, CLIENTID,
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);
}
pubmsg.payload = PAYLOAD;
pubmsg.payloadlen = strlen(PAYLOAD);
pubmsg.qos = QOS;
pubmsg.retained = 0;
MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);
printf("Waiting for up to %d seconds for publication of %s\n"
"on topic %s for client with ClientID: %s\n",
(int)(TIMEOUT/1000), PAYLOAD, TOPIC, CLIENTID);
rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
printf("Message with delivery token %d delivered\n", token);
MQTTClient_disconnect(client, 10000);
MQTTClient_destroy(&client);
return rc;
}
我得到以下信息：
19:31:16 **** Rebuild of configuration Debug for project MQTT_C_Client ****
Info: Internal Builder is used for build
gcc "-IE:\WS\MQTT_C_Client\includes" -O0 -g3 -Wall -c -fmessage-length=0 -o "src\main.o" "..\src\main.c"
gcc "-LE:\WS\MQTT_C_Client\libs" -o MQTT_C_Client.exe "src\main.o" -lpaho-mqtt3a -lpaho-mqtt3as -lpaho-mqtt3c -lpaho-mqtt3cs
src\main.o: In function `main':
E:\WS\MQTT_C_Client\Debug/../src/main.c:29: undefined reference to `MQTTClient_create'
E:\WS\MQTT_C_Client\Debug/../src/main.c:34: undefined reference to `MQTTClient_connect'
E:\WS\MQTT_C_Client\Debug/../src/main.c:43: undefined reference to `MQTTClient_publishMessage'
E:\WS\MQTT_C_Client\Debug/../src/main.c:47: undefined reference to `MQTTClient_waitForCompletion'
E:\WS\MQTT_C_Client\Debug/../src/main.c:49: undefined reference to `MQTTClient_disconnect'
E:\WS\MQTT_C_Client\Debug/../src/main.c:50: undefined reference to `MQTTClient_destroy'
collect2.exe: error: ld returned 1 exit status
19:31:29 Build Finished (took 12s.643ms)
知道我错过了什么吗？
这是一个可能的错误原因。 （可能不是正确的解决方案，具体取决于底层链接器）
是-L相对于-l的位置给你带来了麻烦（我的观察有点粗心）。来自 gcc 联机帮助页：
You can mix options and other arguments. For the most part, the order you use doesn't matter. Order does matter when you use several options of the same kind; for example, if you specify -L more than once, the directories are searched in the order specified. Also, the placement of the -l option is significant.
这可能会有所不同，具体取决于底层链接器 -L 库搜索的范围。尝试确保 -L 和 -l 彼此相邻，没有任何其他直接链接的对象路径将它们分开。
例如，
gcc -o myprog main.o foo.o bar.o -L/some/path -L/some/other/path -la -lb
还可以
然而，
gcc -o myprog main.o -L/some/path foo.o bar.o -L/some/other/path -la -lb
不是。
我通过使用 Cygwin 在 Windows 上构建库并使用生成的库解决了这个问题。