Problems compiling test program program form pgsql

Hi , I've got a problem compiling the test program in the programmers guide.
t frist how I do to link libpg.a in gcc and g++ ?

Later I've got the screen :

$bash: g++ test.C -o test.o -o test /usr/lib/libpg.a // my libpg.a is in /usr/lib
/usr/lib/libpq.a (fe-auth.o) : in function 'pg_password_sendauth' :
fe_auth.o(.text+0x27):undefined reference to 'crypt'
collect2 : ld reurned 1 exit status
$bash :

Note : my computer runs a linux red hat Conectiva 3.0 installed with postgres 6.5.2.

If someone can help-me I will be very gateful .