bool_in bool_out pg_date_in pg_date_out pg_interval_cmp pg_interval_in pg_interval_make pg_interval_mul pg_interval_out pg_interval_pl pg_time_in pg_time_out pg_timestamp_in pg_timestamp_mi pg_timestamp_mi_interval pg_timestamp_out pg_timestamp_pl_interval pg_timestamptz_in pg_timestamptz_out

bool_out() char * bool_out ( bool  b ) Convert 1 or 0 to "t" or "f". Note PostgreSQL function: Datum boolout(PG_FUNCTION_ARGS)