C++ CMake链接问题

我尝试使用CGEL编译一个C++应用程序，使用C库gStuff.< /P> 我的main.cpp文件如下所示：

extern "C" {
#include <gst/gst.h>
#include <glib.h>
}


int main(int argc, char* argv[])
{
  GMainLoop *loop;

  GstElement *pipeline, *source, *demuxer, *decoder, *conv, *sink;
  GstBus *bus;

  /* Initialisation */
  gst_init (&argc, &argv);
  return 0;
}

cmake_minimum_required (VERSION 2.6)
project (MPEG4GStreamer)
add_executable (MPEG4GStreamer main.cpp)
include(${CMAKE_ROOT}/Modules/FindPkgConfig.cmake)

# Set CMAKE_C_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --cflags gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_C_FLAGS)
string(REPLACE "\n" "" CMAKE_C_FLAGS ${CMAKE_C_FLAGS})
message("CMAKE_C_FLAGS: ${CMAKE_C_FLAGS}")

# Set CMAKE_LINKER_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --libs gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_LINKER_FLAGS)
string(REPLACE "\n" "" CMAKE_LINKER_FLAGS ${CMAKE_LINKER_FLAGS})
message("CMAKE_LINKER_FLAGS: ${CMAKE_LINKER_FLAGS}")

set_target_properties(MPEG4GStreamer
                      PROPERTIES COMPILE_FLAGS ${CMAKE_C_FLAGS}
                                 LINKER_FLAGS ${CMAKE_LINKER_FLAGS})

如何使用CMake制作？我的CMakeLists.txt文件如下所示：

extern "C" {
#include <gst/gst.h>
#include <glib.h>
}


int main(int argc, char* argv[])
{
  GMainLoop *loop;

  GstElement *pipeline, *source, *demuxer, *decoder, *conv, *sink;
  GstBus *bus;

  /* Initialisation */
  gst_init (&argc, &argv);
  return 0;
}

cmake_minimum_required (VERSION 2.6)
project (MPEG4GStreamer)
add_executable (MPEG4GStreamer main.cpp)
include(${CMAKE_ROOT}/Modules/FindPkgConfig.cmake)

# Set CMAKE_C_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --cflags gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_C_FLAGS)
string(REPLACE "\n" "" CMAKE_C_FLAGS ${CMAKE_C_FLAGS})
message("CMAKE_C_FLAGS: ${CMAKE_C_FLAGS}")

# Set CMAKE_LINKER_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --libs gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_LINKER_FLAGS)
string(REPLACE "\n" "" CMAKE_LINKER_FLAGS ${CMAKE_LINKER_FLAGS})
message("CMAKE_LINKER_FLAGS: ${CMAKE_LINKER_FLAGS}")

set_target_properties(MPEG4GStreamer
                      PROPERTIES COMPILE_FLAGS ${CMAKE_C_FLAGS}
                                 LINKER_FLAGS ${CMAKE_LINKER_FLAGS})

输出提示链接器错误：

~ $ cmake .
CMAKE_C_FLAGS: -D_REENTRANT -I/usr/include/libxml2 -I/opt/local/include/gstreamer-0.10 -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include  
CMAKE_LINKER_FLAGS: -L/opt/local/lib -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lpthread -lz -lm -lglib-2.0 -lintl -liconv  
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/francis/
~ $ make
Linking CXX executable MPEG4GStreamer
Undefined symbols:
  "_gst_init", referenced from:
      _main in main.cpp.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
make[2]: *** [MPEG4GStreamer] Error 1
make[1]: *** [CMakeFiles/MPEG4GStreamer.dir/all] Error 2
make: *** [all] Error 2
~ $

---

Doh，只需要用CMAKE_EXE_LINKER_标志替换CMAKE_LINKER_标志。

您应该找到库gstreamer-0.10，并使用目标链接库将其链接到您的目标。您需要一个FindGStream.cmake模块，下面是我通过谷歌搜索找到的一个模块：

有了这样的模块，您可能需要这样的内容：

extern "C" {
#include <gst/gst.h>
#include <glib.h>
}


int main(int argc, char* argv[])
{
  GMainLoop *loop;

  GstElement *pipeline, *source, *demuxer, *decoder, *conv, *sink;
  GstBus *bus;

  /* Initialisation */
  gst_init (&argc, &argv);
  return 0;
}

cmake_minimum_required (VERSION 2.6)
project (MPEG4GStreamer)
add_executable (MPEG4GStreamer main.cpp)
include(${CMAKE_ROOT}/Modules/FindPkgConfig.cmake)

# Set CMAKE_C_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --cflags gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_C_FLAGS)
string(REPLACE "\n" "" CMAKE_C_FLAGS ${CMAKE_C_FLAGS})
message("CMAKE_C_FLAGS: ${CMAKE_C_FLAGS}")

# Set CMAKE_LINKER_FLAGS variable with info from pkg-util
execute_process(COMMAND pkg-config --libs gstreamer-0.10
                OUTPUT_VARIABLE CMAKE_LINKER_FLAGS)
string(REPLACE "\n" "" CMAKE_LINKER_FLAGS ${CMAKE_LINKER_FLAGS})
message("CMAKE_LINKER_FLAGS: ${CMAKE_LINKER_FLAGS}")

set_target_properties(MPEG4GStreamer
                      PROPERTIES COMPILE_FLAGS ${CMAKE_C_FLAGS}
                                 LINKER_FLAGS ${CMAKE_LINKER_FLAGS})

包括（FindStreamer.cmake） include_目录（${GSTREAMER_include_DIR}） 添加定义（${GSTREAMER\u definitions}）

---

目标链接库（MPEG4GStreamer${GSTREAMER\u libraries}）

真正的问题是您键入了属性的名称，它是链接标志，而不是链接ER\u标志。您的解决方案只是一个变通办法。

那么您应该结束这个问题