Re: [Boost-users] can't get first example in boost tutorial to work

From: Jens Seidel (jensseidel_at_[hidden])
Date: 2008-04-20 15:49:14

On Sun, Apr 20, 2008 at 07:36:58PM +0000, 7stud wrote:
> Here is the tutorial example:
> 
> #include <boost/lambda/lambda.hpp>
> #include <iostream>
> #include <iterator>
> #include <algorithm>
> 
> int main()
> {
>   using namespace boost::lambda;
>   typedef std::istream_iterator<int> in;
>   
>   std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " );
>   return 0;
> }
> 
> 
> And this is what happens:
> 
> gcc -I /usr/local/boost_1_34_1 prog1.cpp

Please use the C++ compiler "g++" instead of the C compiler "gcc".

> /usr/bin/ld: Undefined symbols:

Ah, OK, now the compiler error vanished as the compiler is able to
find the header files of boost.

[The following can probably be ignored as I missed at the beginning
the you used the C compiler. Nevertheless you may find the next
usful in you later steps:]

Now the linker complains about symbols (such as functions) defined in a
Boost library which you have to link against.

You need for linking the additional options
-L /usr/local/boost_1_34_1/lib/ (to specify the library search path)
-l boost??? (to specify the library)

Sorry, I do not remember the library name which contains lambda. Just
look into your /usr/local/boost_1_34_1/ for available
dynamic lib/libboost*.so or lib/libboost*.a static libraries and choose
the right one (without lib prefix or .so or a suffix).

Please note that this kind of question indicate that you are not very
familiar with a C++ compiler. That's not a problem but please try to find
such answers yourself by following more basic C++/g++ tutorials.

Starting with a simple "Hello world" program is typically the first
step.

Jens