"The program can't start because opencv_world300.dll is missing from your computer" error in C++

Under windows you can copy it from:

<your install directory>\opencv30\build\x64\vc12\bin

And put it in your Visual Studio solution (I assume you are using a x64/Release configuration):

<your solution directory>\x64\Release

Or you you can add the above OpenCV to your PATH environment variable

I had the same problem.

I'm on version 320. Once all your environment variables are set make sure your Additional Include Directories, Additional Library Directories and Additional Dependencies are all correct. For me they were $(OPENCV_BUILD)\include;, $(OPENCV_BUILD)\x64\vc14\lib; and opencv_world320d.lib; respectively.

My OPENCV_BUILD path variable is C:\opencv320\build setting the environment variable to %OPENCV_BUILD%\x64\vc14\bin (where the .dll files are located). To get to the Additional things right-click on your project/solution and select properties -> C/C++ for the first and properties -> Linker -> General and Input for the other two.

Restart Visual Studio and if everything was implemented correctly then you should be able to run the program and it should start.

Edit:

Depending on what you used I had to also switch mine from x86 to x64 in the Solution Platforms dropdown.

You can check your system variable to confirm the directory in which opencv_world300.dll is located (maybe C:\opencv\build\x64\vc12\bin) is present.

If it exists but the problem still is not solved, try to put all .dll files in the directory to C:\WINDOWS\system32