undefined reference to `_com_util::ConvertBSTRToString(wchar_t*)'

yangyanhui4

the following is the .pro file,what have I miss,I have include <comutil>
QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
greaterThan(QT_MAJOR_VERSION, 4): QT += multimedia

TARGET = FFMPEGQT
TEMPLATE = app

The following define makes your compiler emit warnings if you use

any feature of Qt which has been marked as deprecated (the exact warnings

depend on your compiler). Please consult the documentation of the

deprecated API in order to know how to port your code away from it.

DEFINES += QT_DEPRECATED_WARNINGS

You can also make your code fail to compile if you use deprecated APIs.

In order to do so, uncomment the following line.

You can also select to disable deprecated APIs only up to a certain version of Qt.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

INCLUDEPATH += $$PWD/ffmpeg-20200528-c0f01ea-win64-dev/include \

LIBS += $$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/avcodec.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/avdevice.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/avfilter.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/avformat.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/avutil.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/postproc.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/swresample.lib
$$PWD/ffmpeg-20200528-c0f01ea-win64-dev/lib/swscale.lib
LIBS += -lole32
LIBS += -loleaut32
LIBS += -lstrmiids

SOURCES +=
main.cpp
mainwindow.cpp
workthread.cpp

HEADERS +=
mainwindow.h
workthread.h

FORMS +=
mainwindow.ui
UI_DIR=./UI

qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

mrjj

Hi
From here
https://docs.microsoft.com/en-us/cpp/cpp/convertbstrtostring?view=vs-2019
seems you also have to link
comsuppw.lib or comsuppwd.lib

Bonnie

Hi, this is actually not a Qt-related error.
You should learn to read Microsoft API docs, espcially the Requirements part, it tells you the header to include and the lib to link.
Also, when posting, better to wrap your file content with "code" tag (click </>), that'll make it easier to read.

yangyanhui4

i haved added #pragma comment(lib, "comsuppw.lib") but the problem also exists

mrjj

@yangyanhui4

Did you try
LIBS += -lcomsuppw

yangyanhui4

error: cannot find -lcomsuppw

mrjj

@yangyanhui4

Then maybe you dont have it ?
What windows version and compiler are you using ?

yangyanhui4

WIN8.1 QT5.12 mingw 64-bit

Bonnie

Are you using MinGW kit?
This is a MSVC lib. You need to install MSVC build tools and use MSVC version of Qt.