C++ OpenCV include error 'file not found'

Question

I have a problem using OpenCV 4.1.2 in C++. I have this CMakelists.txt:

cmake_minimum_required(VERSION 2.8.12)
project( Barcode-cpp )
find_package( OpenCV REQUIRED )
add_compile_options(-std=c++11)
add_library( src
        src/VideoVeed.h
        src/VideoVeed.cpp
)
add_executable( program
            program/main.cpp
)
target_link_libraries( program
                    src
                    ${OpenCV_LIBS}
)

As you can see I have two folders with source code:

program contains main.cpp
src contains VideoVeed.h & VideoVeed.cpp

When I include OpenCV in main.cpp like this: <opencv2/opencv.hpp>, it works fine. But when I include OpenCV (the same way) it gives the error fatal error: 'opencv2/opencv.hpp' file not found.

I think I'm doing something wrong in my CMakelists.txt, but I can't figure out what exactly.

I hope someone is able to help me. Thanks in advance!

Kevin · Accepted Answer · 2019-11-19 13:22:08Z

2

You should add the line, target_include_directories(), so that the OpenCV include directories are included in your executable:

add_executable( program
        program/main.cpp
)
target_include_directories(program PRIVATE ${OpenCV_INCLUDE_DIR})

Depending on the version of OpenCV you are using, you may need to use OpenCV_INCLUDE_DIRS instead:

add_executable( program
        program/main.cpp
)
target_include_directories(program PRIVATE ${OpenCV_INCLUDE_DIRS})

EDIT: OpenCV 4.1.2 populates the variable OpenCV_INCLUDE_DIRS, so this is the variable you should use. See this tutorial.

edited Nov 19, 2019 at 13:22

answered Nov 19, 2019 at 12:50

Kevin

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5 Comments

mHvNG Over a year ago

unfortunately this doesn't work... Where do I need to put it. Perhaps I placed it at the wrong place?

Kevin Over a year ago

It should be placed after defining your program target, after the call to add_executable().

mHvNG Over a year ago

Hmm, this doesn;t work for me than... Thanks for trying tho!

mHvNG Over a year ago

I have OpenCV 4.1.2 btw, maybe that helps.

Kevin Over a year ago

@mHvNG Yes, the version helps. I edited my answer, and it may help to clear your CMake cache and run CMake from scratch.

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