如何在我的包含路径中添加目录，以避免用C ++编写完整的目录路径？

Question

I'm pretty new to programming and want to use opencv2. I've got a code package and want to run it. It is written in C++ and I want to include several files within opencv2 and the code is:

#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"

My question is why didn't #include give the whole directory like /usr/local/include/opencv2/... ?

This code could not run on my computer because I didn't add opencv2 into my include path.

What should I do?

Answer 1

If your compiler does not automatically look for headers under /usr/local/include , then you need to tell it to do so:

g++ … -I/usr/local/include … source.cpp

The reason that you don't put the full path name into the source is that it makes it unportable. You have OpenCV2 installed in /usr/local , I have it in /opt/OpenCV2 . The source would have to be hacked horribly if the code said:

#include "/usr/local/include/opencv2/core/core.hpp"

The way it is, people can locate the OpenCV2 library and supporting headers in any location and only have to specify that location on the command line (or in the makefile, or let an auto-configuring tool do the work for you).

Answer 2

Add OpenCV2 into your include path.

You can write an absolute path into your #include directive if you want, but it's sorely frowned upon as it makes your code utterly non-portable.