Can I make direct calls to PostgreSQL server?

I am new to this list, forgive me if I do something wrong.

I am writing an application in C++ for Linux to post data to a PostgreSQL 
server.
Can I make direct calls to PostgreSQL server? I have a lot of data to post to 
the local PostgreSQL server. I am wondering if I can connect directly to it 
to post data so I can by pass the extra layers of 
command -> SQL text string -> port -> SQL interpreter -> internal DB command
I would like to go
command -> lib function call  -> internal DB command

All I can find is examples of how to make long text strings of SQL commands 
then pass them to a local port then on into the server. Is this the only way?

-- 
Roy Souther 

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