The libecpg library primarily contains "hidden" functions that are used to implement the functionality expressed by the embedded SQL commands. But there are some functions that can usefully be called directly. Note that this makes your code unportable.
ECPGdebug(int on, FILE *stream) turns on debug logging if called with the first argument non-zero. Debug logging is done on stream. Most SQL statement log their arguments and results.
The most important function, ECPGdo, logs all SQL statements with both the expanded string, i.e. the string with all the input variables inserted, and the result from the PostgreSQL server. This can be very useful when searching for errors in your SQL statements.
ECPGstatus() This method returns true if we are connected to a database and false if not.