Re: libpq-fe: PQgetvalue() ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Christoph Haller <ch(at)rodos(dot)fzk(dot)de>
Cc: sad <sad(at)bankir(dot)ru>, pgsql-sql(at)postgresql(dot)org
Subject: Re: libpq-fe: PQgetvalue() ?
Date: 2004-10-15 14:21:29
Message-ID: 8899.1097850089@sss.pgh.pa.us
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Christoph Haller <ch(at)rodos(dot)fzk(dot)de> writes:
> You cannot PQclear(pgresult_varible) while cstring_varible is in use.
> You do not need to free cstring_variable, PQclear(pgresult_varible) will do.
> I personally prefer to allocate local memory, "strcpy" PQgetvalue,
> and then PQclear. But that's a matter of taste, I suppose.

That is surely overkill.

PQgetvalue doesn't allocate new memory for its result. The docs are
reasonably clear, I thought:

The pointer returned by PQgetvalue points to storage that is part
of the PGresult structure. One should not modify the data it points
to, and one must explicitly copy the data into other storage if it
is to be used past the lifetime of the PGresult structure itself.

regards, tom lane

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