How do you find libraries (C++) in Ubuntu?

By default libraries are installed in /usr/lib and header files will be in /usr/include

Usually extension of the library file is .so and corresponding header file will be .h

gui method for finding installed libraries is open software center->Developer tools-> Libraries

The brute strength approach is:

sudo updatedb
locate libpcl

Updatedb takes a few moments; please be patient. The library you're looking for is likely in /usr/lib.