Karl answered your search-path question, but as far as the "source of the files" goes, one thing to be aware of is that if you install the libfoo
package and want to do some development with it (i.e., use its headers), you will also need to install libfoo-dev
. The standard library header files are already in /usr/include
, as you saw.
Note that some libraries with a lot of headers will install them to a subdirectory, e.g., /usr/include/openssl
. To include one of those, just provide the path without the /usr/include
part, for example:
#include <openssl/aes.h>