PaError 不是类或命名空间答案

【问题标题】：PaError not a class or namespacePaError 不是类或命名空间
【发布时间】：2018-04-03 19:19:36
【问题描述】：

我一直在尝试将 portaudio 包含到我的 c++ 项目中，但似乎包含一些问题，因为我的项目不“知道”portaudio 命名空间，但是 qt 自动完成函数名称，就好像它知道他们。

源码目录：

├── CMakeLists.txt
├── CMakeLists.txt.user
└── src
    ├── CMakeLists.txt
    ├── include
    │   ├── CMakeLists.txt
    │   ├── database
    │   │   ├── CMakeLists.txt
    │   │   ├── database.cpp
    │   │   └── database.h
    │   ├── match
    │   │   ├── CMakeLists.txt
    │   │   ├── match.cpp
    │   │   └── match.h
    │   ├── record
    │   │   ├── CMakeLists.txt
    │   │   ├── record.cpp
    │   │   └── record.h
    │   └── spectogram
    │       ├── CMakeLists.txt
    │       ├── spectogram.cpp
    │       └── spectogram.h
    └── main.cpp

portaudio 教程建议，要在 linux 环境中构建 portaudio，需要从 portaudio 源文件中复制当前驻留在 audio/portaudio 中的文件，这显然就足够了。

CMakeLists.txt within record:
MESSAGE( “In reord CMAKELIST” )
MESSAGE(":" <Project_source_dir> )
# Include externalproject {portaudio} if lib/portaudio don't exist.

INCLUDE(ExternalProject)
ExternalProject_Add(project_portaudio
    GIT_REPOSITORY      https://git.assembla.com/portaudio.git
    PREFIX              lib/portaudio
    UPDATE_COMMAND      ""
    CONFIGURE_COMMAND   <SOURCE_DIR>/configure
    BUILD_IN_SOURCE     0
    BUILD_COMMAND       make
    INSTALL_COMMAND     sudo make install
)
ExternalProject_Get_Property(project_portaudio BINARY_DIR)
ExternalProject_Get_Property(project_portaudio SOURCE_DIR)

SET(portaudio_lib_dir "${BINARY_DIR}/lib/.libs")
SET(portaudio_inc_dir "${SOURCE_DIR}/include")

add_library(record STATIC record.cpp record.h)

add_library(portaudio STATIC IMPORTED)
set_target_properties(portaudio PROPERTIES
    IMPORTED_LOCATION "${portaudio_lib_dir}/libportaudio.a")

set_property(TARGET portaudio APPEND PROPERTY
    INTERFACE_INCLUDE_DIRECTORIES ${SOURCE_DIR}/include)

add_dependencies(portaudio project_portaudio)     # Not sure if this is allowed for imported targets though

find_package(Threads REQUIRED)
find_package(ALSA REQUIRED)

IF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
   SET(EXTRA_LIBS rt asound jack)
ENDIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")

#
# this makes sure we have compiler flags that allow class::class() = default (>= C++11)
target_link_libraries(record PUBLIC  ${EXTRA_LIBS} Threads::Threads portaudio)
target_compile_features(record PUBLIC cxx_defaulted_functions)
target_include_directories(record PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} ${project_portaudio})

main.cpp:

#include <iostream>
#include "record.h"

using namespace std;

int main()
{
    record test;
    test.example();

    cout << "Hello World!" << endl;
    return 0;
}

记录.cpp：

#include "record.h"

record::record()
{
    std::cout << "Record Created!" << std::endl;
}

void record::example()
{
    std::cout << "In example!" << std::endl;
    std::cout << Pa_GetVersion() << std::endl;
}

记录.h

#ifndef RECORD_H
#define RECORD_H
#include <iostream>
#include "portaudio.h"

class record
{
public:
    record();
    void example();
};

#endif // RECORD_H

我尝试将 portaudio 包含在我的记录类中，并查看它是否理解 portaudio 功能，例如 Pa_getversion.. 但我似乎收到了如下错误消息：

/home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:421: undefined reference to `snd_pcm_hw_params_set_buffer_size_near'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:422: undefined reference to `snd_pcm_hw_params_set_buffer_size_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:424: undefined reference to `snd_pcm_hw_params_set_period_size_near'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:425: undefined reference to `snd_pcm_hw_params_set_periods_integer'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:426: undefined reference to `snd_pcm_hw_params_set_periods_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:428: undefined reference to `snd_pcm_hw_params_get_buffer_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:433: undefined reference to `snd_pcm_hw_params_get_channels_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:434: undefined reference to `snd_pcm_hw_params_get_channels_max'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:436: undefined reference to `snd_pcm_hw_params_test_period_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:437: undefined reference to `snd_pcm_hw_params_test_format'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:438: undefined reference to `snd_pcm_hw_params_test_access'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:439: undefined reference to `snd_pcm_hw_params_dump'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:440: undefined reference to `snd_pcm_hw_params'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:442: undefined reference to `snd_pcm_hw_params_get_periods_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:443: undefined reference to `snd_pcm_hw_params_get_periods_max'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:444: undefined reference to `snd_pcm_hw_params_set_period_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:445: undefined reference to `snd_pcm_hw_params_get_period_size_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:446: undefined reference to `snd_pcm_hw_params_get_period_size_max'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:447: undefined reference to `snd_pcm_hw_params_get_buffer_size_max'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:448: undefined reference to `snd_pcm_hw_params_get_rate_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:449: undefined reference to `snd_pcm_hw_params_get_rate_max'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:450: undefined reference to `snd_pcm_hw_params_get_rate_numden'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:452: undefined reference to `snd_pcm_sw_params_sizeof'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:453: undefined reference to `snd_pcm_sw_params_malloc'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:454: undefined reference to `snd_pcm_sw_params_current'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:455: undefined reference to `snd_pcm_sw_params_set_avail_min'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:456: undefined reference to `snd_pcm_sw_params'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:457: undefined reference to `snd_pcm_sw_params_free'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:458: undefined reference to `snd_pcm_sw_params_set_start_threshold'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:459: undefined reference to `snd_pcm_sw_params_set_stop_threshold'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:460: undefined reference to `snd_pcm_sw_params_get_boundary'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:461: undefined reference to `snd_pcm_sw_params_set_silence_threshold'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:462: undefined reference to `snd_pcm_sw_params_set_silence_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:463: undefined reference to `snd_pcm_sw_params_set_xfer_align'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:464: undefined reference to `snd_pcm_sw_params_set_tstamp_mode'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:466: undefined reference to `snd_pcm_info'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:467: undefined reference to `snd_pcm_info_sizeof'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:468: undefined reference to `snd_pcm_info_malloc'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:469: undefined reference to `snd_pcm_info_free'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:470: undefined reference to `snd_pcm_info_set_device'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:471: undefined reference to `snd_pcm_info_set_subdevice'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:472: undefined reference to `snd_pcm_info_set_stream'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:473: undefined reference to `snd_pcm_info_get_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:474: undefined reference to `snd_pcm_info_get_card'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:476: undefined reference to `snd_ctl_pcm_next_device'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:477: undefined reference to `snd_ctl_pcm_info'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:478: undefined reference to `snd_ctl_open'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:479: undefined reference to `snd_ctl_close'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:480: undefined reference to `snd_ctl_card_info_malloc'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:481: undefined reference to `snd_ctl_card_info_free'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:482: undefined reference to `snd_ctl_card_info'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:483: undefined reference to `snd_ctl_card_info_sizeof'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:484: undefined reference to `snd_ctl_card_info_get_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:486: undefined reference to `snd_config'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:487: undefined reference to `snd_config_update'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:488: undefined reference to `snd_config_search'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:489: undefined reference to `snd_config_iterator_entry'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:490: undefined reference to `snd_config_iterator_first'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:491: undefined reference to `snd_config_iterator_end'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:492: undefined reference to `snd_config_iterator_next'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:493: undefined reference to `snd_config_get_string'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:494: undefined reference to `snd_config_get_id'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:495: undefined reference to `snd_config_update_free_global'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:497: undefined reference to `snd_pcm_status'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:498: undefined reference to `snd_pcm_status_sizeof'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:499: undefined reference to `snd_pcm_status_get_tstamp'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:500: undefined reference to `snd_pcm_status_get_state'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:501: undefined reference to `snd_pcm_status_get_trigger_tstamp'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:502: undefined reference to `snd_pcm_status_get_delay'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:504: undefined reference to `snd_card_next'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:505: undefined reference to `snd_asoundlib_version'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:506: undefined reference to `snd_strerror'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/alsa/pa_linux_alsa.c:507: undefined reference to `snd_output_stdio_attach'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `GetStreamTime':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1738: undefined reference to `jack_frame_time'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1738: undefined reference to `jack_get_sample_rate'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `UpdateQueue':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1427: undefined reference to `jack_get_sample_rate'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `JackCallback':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1562: undefined reference to `jack_port_get_buffer'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `RealProcess':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1349: undefined reference to `jack_get_sample_rate'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1365: undefined reference to `jack_frame_time'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1367: undefined reference to `jack_port_get_latency'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1370: undefined reference to `jack_port_get_latency'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1391: undefined reference to `jack_port_get_buffer'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1402: undefined reference to `jack_port_get_buffer'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `RealStop':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1688: undefined reference to `jack_port_connected'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1690: undefined reference to `jack_port_disconnect'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1696: undefined reference to `jack_port_connected'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1698: undefined reference to `jack_port_disconnect'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `StartStream':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1609: undefined reference to `jack_port_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1609: undefined reference to `jack_port_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1609: undefined reference to `jack_connect'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1619: undefined reference to `jack_port_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1619: undefined reference to `jack_port_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1619: undefined reference to `jack_connect'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `CleanUpStream':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:983: undefined reference to `jack_port_unregister'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:988: undefined reference to `jack_port_unregister'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `OpenStream':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1080: undefined reference to `jack_port_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1081: undefined reference to `jack_client_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1087: undefined reference to `jack_get_sample_rate'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1181: undefined reference to `jack_get_sample_rate'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1214: undefined reference to `jack_port_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1215: undefined reference to `jack_port_register'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1224: undefined reference to `jack_port_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1225: undefined reference to `jack_port_register'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1241: undefined reference to `jack_get_ports'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1245: undefined reference to `jack_port_by_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1265: undefined reference to `jack_get_ports'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1269: undefined reference to `jack_port_by_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1301: undefined reference to `jack_port_get_latency'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1302: undefined reference to `jack_get_buffer_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1305: undefined reference to `jack_port_get_latency
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:733: undefined reference to `jack_client_open'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `BuildDeviceList':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:491: undefined reference to `jack_client_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:492: undefined reference to `jack_client_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:499: undefined reference to `jack_get_ports'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:517: undefined reference to `jack_client_name_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:558: undefined reference to `jack_get_sample_rate'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:589: undefined reference to `jack_get_ports'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:596: undefined reference to `jack_port_by_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:598: undefined reference to `jack_port_get_latency'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:610: undefined reference to `jack_get_ports'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:617: undefined reference to `jack_port_by_name'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:619: undefined reference to `jack_port_get_latency'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `PaJack_Initialize':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:781: undefined reference to `jack_on_shutdown'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:782: undefined reference to `jack_set_error_function'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:783: undefined reference to `jack_get_buffer_size'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:785: undefined reference to `jack_set_sample_rate_callback'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:786: undefined reference to `jack_set_xrun_callback'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:800: undefined reference to `jack_client_close'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:787: undefined reference to `jack_set_process_callback'
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:788: undefined reference to `jack_activate'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `PaJack_SetClientName':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1750: undefined reference to `jack_client_name_size'
    include/record/lib/portaudio/src/project_portaudio-build/lib/.libs/libportaudio.a(pa_jack.o): In function `PaJack_GetClientName':
    /home/lambda/soundcloud/build/src/include/record/lib/portaudio/src/project_portaudio/src/hostapi/jack/pa_jack.c:1765: undefined reference to `jack_get_client_name'
    collect2: error: ld returned 1 exit status
    make[2]: *** [src/cmakeDemo] Error 1
    make[1]: *** [src/CMakeFiles/cmakeDemo.dir/all] Error 2
    make: *** [all] Error 2

【问题讨论】：

根据this documentation，我们有typedef int PaError。所以编译器是对的，它不是类或命名空间，不能那样使用。
所以我应该能够在没有任何命名空间的情况下打印它？.. 似乎不是这样？
或者像 Pa_GetVersion() 这样的东西应该可以在没有任何命名空间的情况下打印...
嗯，是的，如果您查看source code，任何地方都没有命名空间！？ PaError:: 作为命名空间也很奇怪，如果有命名空间那么更像Pa::GetVersion()
在您的CMakeLists.txt 末尾添加target_link_libraries(${PROJECT_NAME} portaudio)。 example() 成员函数的最后一行应该是 std::cout << Pa_GetVersion() << std::endl;。通过这些更改，我可以编译和运行您的示例。

标签： c++ cmake linker namespaces portaudio

【解决方案1】：

QtCreator 确实会查看您的文件系统。因此，它会找到不在您的 CMakeLists.txt 范围内的文件。据我所知，这也适用于自动完成。

在我们的 CMakeLists.txt 中，没有将静态库添加到您的项目的行。像

add_library(libaudio NAME libportaudio.a PATHS ${CMAKE_CURRENT_SOURCE_DIR}/portaudio)
...

add_executable(${PROJECT_NAME} ${SRC_LIST})
target_link_libraries(${PROJECT_NAME} ${libaudio})

好像不见了。

尝试将 libportaudio 构建为共享库。阅读构建说明或致电 portaudio 的./configure --help 以获取更多详细信息。

【讨论】：

我试过了……在我的 target_link_libraries 中添加 portaudio 时，我似乎遇到了其他链接错误。与 ALSA 和 Jack 相关的函数的未定义引用问题。
这也必须解决。您是否在 linux portaudio.com/docs/v19-doxydocs/compile_linux.html 阅读了 portaudio 的构建说明？你执行sudo apt-get install libasound-dev了吗？
关于共享.. 它是标准的。
在 CMakeLists.txt 中使用 libaudioport.so 而不是 libaudioport.a。您的日志仅包含链接器错误，不是吗？您可以通过从命令行触发构建来查看此内容。运行'make'并检查编译器或链接器是否产生错误。
嗯.. 这些是未定义的引用.. 我在 target_link_libraries 添加 portaudio 后得到了这些..

【解决方案2】：

它似乎不喜欢。 PaError 不是类或命名空间？

查看此处记录的代码：

http://portaudio.com/docs/v19-doxydocs/portaudio_8h_source.html

演出：

~剪辑

   #ifdef __cplusplus
   49 extern "C"
   50 {
   51 #endif /* __cplusplus */
   52 
   58 int Pa_GetVersion( void );
   59 
   67 const char* Pa_GetVersionText( void );
   68 
   81 #define paMakeVersionNumber(major, minor, subminor) \
   82     (((major)&0xFF)<<16 | ((minor)&0xFF)<<8 | ((subminor)&0xFF))
   83 
   84 
   90 typedef struct PaVersionInfo {
   91     int versionMajor;
   92     int versionMinor;
   93     int versionSubMinor;
   99     const char *versionControlRevision;
  101     const char *versionText;
  102 } PaVersionInfo;
  103     
  114 const PaVersionInfo* Pa_GetVersionInfo();
  115 
  116 
  121 typedef int PaError;  
  ...

基于此，它似乎没有使用任何自定义 C++ 命名空间。

PaError 只是定义为一个 int。

所以你的代码：

std::cout << PaError::Pa_GetVersion() << std::endl;

本质上试图将 int 视为包含 Pa_GetVersion() 方法的类类型。这对于您遇到的错误是有道理的。

从头文件来看，Pa_GetVersion() 似乎是标准 C 风格的导出函数，如 portaudio.h 中所列：

58 int Pa_GetVersion( void );

因此，您应该能够简单地按原样调用该函数。所以尝试将您的代码更改为：

std::cout << Pa_GetVersion() << std::endl;

它看起来应该返回一个 int。

【讨论】：