compile and run basic opencv program in C in ubuntu linaro

[Riwa]

[sebraa]

Cmake is a high-level build tool, which produces Makefiles (among others) from CMakeLists.txt specifying your code for you.
You have to call it with the path to the directory containing the CMakeLists.txt, so call it with "cmake ." (include the dot).
Then it should generate a Makefile, which you utilize by doing "make".

[Riwa]

[sebraa]

The Makefile contains a rule to create a .o-file from a .cpp file.
So if it says that there is no rule to make "example.o" then that tells you that there is no "example.cpp" file.

Note: A .o-file is a binary, already-compiled file. So you should never copy a .o-file to fix a build.

This file is listed in your CMakeLists.txt as well. So if you have your code in "foo.cpp", then update your CMakeLists.txt to reference foo.cpp, then run "cmake ." to create a new Makefile, then run "make" to build your program.