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我有一个来自相机制造商的库，在提供的演示代码中，一个名为 metadata_init() 的函数工作正常，但在我的代码中，我收到 undefined reference 错误。
演示代码的 make 输出:
/opt/linaro-multilib-2013.09-gcc4.8/bin/arm-linux-gnueabihf-gcc -lm -g -L"/home/aro/Downloads" -o hicore demoS2.c -lpthread -lyuvlib -lrt
就是这样，构建成功，我将在那里有一个工作的 ./hicore 应用程序。
我的项目比较复杂，用eclipse编译。 控制台输出为:
11:33:23 **** Build of configuration Camera-R4-Debug for project Camera ****
make all
Building file: ../src/Camera.cpp
Invoking: Cross G++ Compiler
arm-linux-gnueabihf-g++ -I/opt/Camerasdk/R4/include -I"/cameraBuilds/Wrapper/include" -I"/opt/ExternalLibraries/curl/Camera/R4/include" -I"/opt/ExternalLibraries/libxml2/Camera/R4/include" -I"/opt/ExternalLibraries/OpenCV24/Camera/R4/include" -I"/home/aro/cameraBuilds/Camera" -I/opt/InternalLibraries/include -I/opt/InternalLibraries/include_linux -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/Camera.d" -MT"src/Camera.o" -o "src/Camera.o" "../src/Camera.cpp"
../src/Camera.cpp: In function ‘int metadata_construct_http_message(char*, METADATA_HTTP_MESSAGE_TYPE, void*, int*)’:
../src/Camera.cpp:379:24: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
"</svg>\r\n";
^
../src/Camera.cpp: In function ‘int main()’:
../src/Camera.cpp:426:97: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
(void)metadata_init("stream.cgi", strlen("stream.cgi"), metadata_construct_http_message);
^
Finished building: ../src/Camera.cpp
Building file: ../src/CameraFrameGrabber.cpp
Invoking: Cross G++ Compiler
arm-linux-gnueabihf-g++ -I/opt/Camerasdk/R4/include -I"/cameraBuilds/Wrapper/include" -I"/opt/ExternalLibraries/curl/Camera/R4/include" -I"/opt/ExternalLibraries/libxml2/Camera/R4/include" -I"/opt/ExternalLibraries/OpenCV24/Camera/R4/include" -I"/home/aro/cameraBuilds/Camera" -I/opt/InternalLibraries/include -I/opt/InternalLibraries/include_linux -I/opt/InternalLibraries/ipslib/include -I/opt/InternalLibraries/ipsstream/include -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/CameraFrameGrabber.d" -MT"src/CameraFrameGrabber.o" -o "src/CameraFrameGrabber.o" "../src/CameraFrameGrabber.cpp"
Finished building: ../src/CameraFrameGrabber.cpp
Building file: ../src/CameraLogger.cpp
Invoking: Cross G++ Compiler
arm-linux-gnueabihf-g++ -I/opt/Camerasdk/R4/include -I"/home/aro/cameraBuilds/Wrapper/include" -I"/opt/ExternalLibraries/curl/Camera/R4/include" -I"/opt/ExternalLibraries/libxml2/Camera/R4/include" -I"/opt/ExternalLibraries/OpenCV24/Camera/R4/include" -I"/home/aro/cameraBuilds/Camera" -I/opt/InternalLibraries/include -I/opt/InternalLibraries/include_linux -I/opt/InternalLibraries/ipslib/include -I/opt/InternalLibraries/ipsstream/include -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/CameraLogger.d" -MT"src/CameraLogger.o" -o "src/CameraLogger.o" "../src/CameraLogger.cpp"
Finished building: ../src/CameraLogger.cpp
Building file: ../src/CameraParameter.cpp
Invoking: Cross G++ Compiler
arm-linux-gnueabihf-g++ -I/opt/Camerasdk/R4/include -I"/home/aro/cameraBuilds/Wrapper/include" -I"/opt/ExternalLibraries/curl/Camera/R4/include" -I"/opt/ExternalLibraries/libxml2/Camera/R4/include" -I"/opt/ExternalLibraries/OpenCV24/Camera/R4/include" -I"/home/aro/cameraBuilds/Camera" -I/opt/InternalLibraries/include -I/opt/InternalLibraries/include_linux -I/opt/InternalLibraries/ipslib/include -I/opt/InternalLibraries/ipsstream/include -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/CameraParameter.d" -MT"src/CameraParameter.o" -o "src/CameraParameter.o" "../src/CameraParameter.cpp"
Finished building: ../src/CameraParameter.cpp
Building target: Camera
Invoking: Cross G++ Linker
arm-linux-gnueabihf-g++ -L/opt/Camerasdk/R4/lib -L"/cameraBuilds/Wrapper/Camera-R4-Debug" -L"/opt/ExternalLibraries/curl/Camera/R4/lib" -L"/opt/ExternalLibraries/libxml2/Camera/R4/lib" -L"/opt/ExternalLibraries/OpenCV24/Camera/R4/lib" -L"/opt/DetectionModules/Camera/R4/lib" -L/home/aro/Downloads -o "Camera" ./src/Camera.o ./src/CameraFrameGrabber.o ./src/CameraLogger.o ./src/CameraParameter.o -lWrapper -lxml2 -lopencv_highgui -lopencv_imgproc -lopencv_core -lpthread -lyuvlib -lrt -llibjasper -llibjpeg -llibpng -llibtiff -lzlib -lcurl
./src/Camera.o: In function `main':
/home/aro/cameraBuilds/Camera/Camera-R4-Debug/../src/Camera.cpp:426: undefined reference to `metadata_init(char*, int, int (*)(char*, METADATA_HTTP_MESSAGE_TYPE, void*, int*))'
collect2: error: ld returned 1 exit status
make: *** [Camera] Error 1
11:33:24 Build Finished (took 1s.212ms)
代码本身是一回事，我只是复制过来。
元数据.h:
#ifndef _HIK_METADATA_H_
#define _HIK_METADATA_H_
const int max_http_body_len = 100 * 1024;
typedef enum
{
CMD_ADD_TYPE = 1,
CMD_OTHER,
} METADATA_CTRL_TYPE;
typedef struct
{
int length;
int fd;
METADATA_CTRL_TYPE cmd_type;
} METADATA_HEADER;
typedef struct
{
char option[128];
int share_socket;
} METADATA_ADD_CFG;
typedef enum
{
HTTP_HEADER_TYPE = 1,
HTTP_BODY_TYPE,
} METADATA_HTTP_MESSAGE_TYPE;
typedef struct
{
char boundary[64];
char http_content_type[64];
char multipart_content_type[64];
} METADATA_MULTIPART_TYPE;
typedef int (*p_metadata_construct_http_msg_callback_f)(char *p_option, METADATA_HTTP_MESSAGE_TYPE cmd_type, void *p_data, int *p_data_len);
int metadata_init(char *p_metadata_url, int url_len, p_metadata_construct_http_msg_callback_f p_callback_f);
#endif
在 Camera.cpp 中:
#include "Metadata.h"
int metadata_construct_http_message(char *p_option, METADATA_HTTP_MESSAGE_TYPE cmd_type, void *p_data, int *p_data_len)
{
// Removed for SO
return 0;
}
int main()
{
(void)metadata_init("stream.cgi", strlen("stream.cgi"), metadata_construct_http_message);
...
}
是什么原因造成的，我该如何调试这个问题以缩小解决范围？