OpenCV error

[Vijaykarthikeyan]

How to diagonise it

[Vijaykarthikeyan]

@JonB you're absolutely correct..Thanks for clarifying me.Actually,For the previous projects using opencv..i have included one line which I'm missing in this that's why error hits.

Actually when linking third party libraries against to Qt..we must include it's path to qmake flags.

So, we must include this:

# Add the include path to QMAKE_CXXFLAGS
QMAKE_CXXFLAGS += -I$$PWD/C:/opencv2/include

[jsulm]

@Vijaykarthikeyan There is nothing to diagnose, simply deploy missing library together with your application

[Vijaykarthikeyan]

@jsulm

already included before asking this question...but till now..unable to diagnose

[jsulm]

@Vijaykarthikeyan I'm not talking about project configuration and build but about deployment
https://doc.qt.io/qt-6/deployment.html

The application needs the library at runtime, so it needs to be deployed together with the application.

[JonB]

@Vijaykarthikeyan
I don't understand: you are using -llib....dll as libraries to link against, how does that work? But in any case the error is a runtime error failing to locate the .dll file, I don't see how that is connected to linking.

[Vijaykarthikeyan]

@JonB

i didnt changed the library name..can i change that

[jsulm]

@Vijaykarthikeyan What @JonB means is that on Windows you need *.lib files for -l and *.dll at runtime. So, you -l are wrong.

[Vijaykarthikeyan]

@jsulm yes ofcourse lib for static and dll for runtime..but how to correclty link the .dll file in .pro..please someone guide me

[jsulm]

@Vijaykarthikeyan said in OpenCV error:

yes ofcourse lib for static and dll for runtime

NO! You're not using static libs!
Again: you do not link dll files, you link lib files:

-lNAME_OF_THE_LIB.lib

When deploying the app you deploy dll files. Please read the link I gave you. And also https://doc.qt.io/qt-6/windows-deployment.html

[JonB]

@Vijaykarthikeyan said in OpenCV error:

but how to correclty link the .dll file in .pro..please someone guide me

You don't link to .dll files. You don't mention .dll files in a .pro file. You need to stick to examples, they don't.
OK, I think I see, they name the library files lib....dll.a.
I don't use Windows/MinGW, is it supposed to be -lopencv....dll? Without the leading lib?
But if your code links fine with what you have in the .pro file that's fine.

@jsulm

-lNAME_OF_THE_LIB.lib

I think we are talking MinGW not MSVC here? lib....a files.

At runtime your program has to find libopen....dll file. That needs to be in the same directory as the executable or specified in PATH. I think yours is not? Where is libopencv_....dll per error message, I only see libopencv....dll.a?

[Vijaykarthikeyan]

@JonB you're absolutely correct..Thanks for clarifying me.Actually,For the previous projects using opencv..i have included one line which I'm missing in this that's why error hits.

Actually when linking third party libraries against to Qt..we must include it's path to qmake flags.

So, we must include this:

# Add the include path to QMAKE_CXXFLAGS
QMAKE_CXXFLAGS += -I$$PWD/C:/opencv2/include

[jsulm]

@Vijaykarthikeyan said in OpenCV error:

QMAKE_CXXFLAGS += -I$$PWD/C:/opencv2/include

This is actually done using INCLUDEPATH in pro file

[Vijaykarthikeyan]

@jsulm so like this:
INCLUDEPATH += -I$$PWD/C:/opencv2/include

[jsulm]

@Vijaykarthikeyan No, like shown in the documentation and the screenshot you posted: https://doc.qt.io/qt-6/qmake-variable-reference.html#includepath

[Vijaykarthikeyan]

@jsulm oh..yes..NOw I understood..Thank you