Thread

1. Re: [INTERFACES] C & C ++Program Problem

   Arindam Haldar <arindamhaldar@hotpop.com> — 2002-05-16T12:19:17Z

   on my RedHat 7.2 i have inserted these lines in the file /etc/ld.so.conf
   /usr/lib/pgsql-7.2
   using gcc -lpq egtry.c gives error-->
   /usr/bin/ld: cannot find -lpq
   collect2: ld reurned 1 exit status
   
   am very newto c , can u tellhow to use -lpq ??
   thanx in anticipation
   A.H
   
   Ted Petrosky wrote:
   
   > I was having the same problems. Do you have the momjiam book 
   > PostgreSQL? He gives examples of compiling C and C++ programs complete 
   > with the command line to start compiling (on page 195). Take a look at it (I 
   > think it is also online).  You are missing the linking flag that  tells the linker 
   > where the libpq.a and libpq++.a files live. libpq.a and libpq++.a is where those 
   > symbols are defined.
   > 
   > Ted
   > 
   > 
   > 
   > -----Original Message-----
   > From: Arindam Haldar <arindamhaldar@hotpop.com>
   > To: pgsql-interfaces@postgresql.org, pgsql-general@postgresql.org, 
   > nandrews@investsystems.co.uk
   > Date: Thu, 16 May 2002 12:23:19 +0530
   > Subject: Re: [INTERFACES] C & C ++Program Problem
   > 
   > 
   >>hi,
   >>thanx for the hint. am re-entering c programming from DOS world !--my 
   >>apologies as am again a learner. 1 more Query on to this.
   >>POstgres-7.2 was not configured with-->--with-gnu-ld , which i just saw 
   >>is default set to no... So can that be problem while compling C & C++ 
   >>prorgrames ?
   >>thanx again in advance for ur help.
   >>A.H
   >>
   >>Nigel J. Andrews wrote:
   >>
   >>
   >>You need to read the error messages. It's not a postgres issue it's a 
   >>linking
   >>issue. Try giving the -lpq flag to gcc.
   >>
   >>On Thu, 16 May 2002, Arindam Haldar wrote:
   >>
   >>hi all,
   >>am trying to use C & C++ libraries with postgresql 7.2.
   >>while compiling a sample programe(attached) there were thse errors 
   >>encounterd !..
   >>
   >>[arindam@my src]$
   >>[arindam@my src]$ gcc egTry.c
   >>/tmp/ccTLiExh.o: In function `main':
   >>/tmp/ccTLiExh.o(.text+0x12): undefined reference to `PQconnectdb'
   >>/tmp/ccTLiExh.o(.text+0x2b): undefined reference to `PQstatus'
   >>/tmp/ccTLiExh.o(.text+0x5c): undefined reference to `PQerrorMessage'
   >>/tmp/ccTLiExh.o(.text+0xac): undefined reference to `PQexec'
   >>/tmp/ccTLiExh.o(.text+0xc5): undefined reference to `PQresultStatus'
   >>/tmp/ccTLiExh.o(.text+0xf3): undefined reference to `PQclear'
   >>/tmp/ccTLiExh.o(.text+0x104): undefined reference to `PQfinish'
   >>/tmp/ccTLiExh.o(.text+0x12e): undefined reference to `PQntuples'
   >>/tmp/ccTLiExh.o(.text+0x159): undefined reference to `PQgetvalue'
   >>/tmp/ccTLiExh.o(.text+0x186): undefined reference to `PQclear'
   >>/tmp/ccTLiExh.o(.text+0x197): undefined reference to `PQfinish'
   >>collect2: ld returned 1 exit status
   >>[arindam@my src]$
   >>
   >>lib & include dir are in /usr/lib/pgsql-7.2 & /usr/include/pgsql-7.2.
   >>i have tried to compliethis programme with RH7.2(with postgres rpm & a 
   >>configured from tar file)..
   >>i need help pls...   i want to use C or C++
   >>thanking u in advance
   >>A.H
   >>
   >>
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2. Re: [INTERFACES] C & C ++Program Problem

   Doug McNaught <doug@wireboard.com> — 2002-05-16T12:49:02Z

   Arindam Haldar <arindamhaldar@hotpop.com> writes:
   
   > on my RedHat 7.2 i have inserted these lines in the file /etc/ld.so.conf
   > /usr/lib/pgsql-7.2
   
   This may or may not be necessary, but if you do it you need to run
   'ldconfig' in order for it to take effect.
   
   > using gcc -lpq egtry.c gives error-->
   > /usr/bin/ld: cannot find -lpq
   > collect2: ld reurned 1 exit status
   
   You need to add a -L flag to the compile so gcc looks in the right
   place for libraries.  Also, the '-lpq' should go *after* your source
   file name.  So:
   
   gcc -o egtry egtry.c -L/usr/lib/pgsql-7.2 -lpq 
   
   That should get you a lot closer to working.
   
   -Doug