Обсуждение: libpq usage from C++

Hi, ALL,

Does anybody use libpq from C++?

C++ introduces STL.
C++ introduces smart-pointers.

Is there a simple way of using those writing libpq communication?

Or should I just forget about them and use good old "dump pointers"?

Thank you.

On 3/13/26 9:40 PM, Igor Korot wrote:
> Hi, ALL,
> 
> Does anybody use libpq from C++?

Search engine of choice:

libpq c++

yields:

https://pqxx.org/development/libpqxx/

> 
> C++ introduces STL.
> C++ introduces smart-pointers.
> 
> Is there a simple way of using those writing libpq communication?
> 
> Or should I just forget about them and use good old "dump pointers"?
> 
> Thank you.
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On Sat, Mar 14, 2026 at 5:41 AM Igor Korot <ikorot01@gmail.com> wrote:
> Does anybody use libpq from C++?

Yes

> C++ introduces STL.
> C++ introduces smart-pointers.
> Is there a simple way of using those writing libpq communication?
> Or should I just forget about them and use good old "dump pointers"?

Using an existing wrapper is simplest, of course.
We wrote our own. To each its own. E.g.

PS: Avoid the fwd-decl by using the actual libpq headers instead.

extern "C" {

struct pg_conn;
struct pg_result;
typedef struct pg_conn PGconn;
typedef struct pg_result PGresult;
typedef struct _PQconninfoOption PQconninfoOption;
typedef struct pgNotify PGnotify;
void PQfreemem(void *ptr);
void PQclear(PGresult* res);
void PQfinish(PGconn* conn);
void PQconninfoFree(PQconninfoOption* conn);

} // extern "C"

namespace acme::postgresql {

struct PGDeleterFunctor {
    void operator()(PGresult* r) {
        if (r != nullptr) {
            PQclear(r);
        }
    }
    void operator()(PGconn* c) {
        if (c != nullptr) {
            PQfinish(c);
        }
    }
    void operator()(PQconninfoOption* c) {
        if (c != nullptr) {
            PQconninfoFree(c);
        }
    }
    void operator()(PGnotify* n) {
        if (n != nullptr) {
            PQfreemem(n);
        }
    }
};
using PGresult_uptr     = std::unique_ptr<PGresult,         PGDeleterFunctor>;
using PGconn_uptr       = std::unique_ptr<PGconn,           PGDeleterFunctor>;
using PGconninfo_uptr   = std::unique_ptr<PQconninfoOption, PGDeleterFunctor>;
using PGnotify_uptr     = std::unique_ptr<PGnotify,         PGDeleterFunctor>;

...
}

Then we have higher-level wrappers that compose those RAII low-level ones. --DD