BOOST_FOREACH and maps

18 Sep 2006

      OK, I know BOOST_FOREACH isn't part of the official (1.33.1) build yet, but 
hopefully some people here are using this excellent algorithm and can help 
me out... (note that I am using MS Visual Studio 2005):

How can I use BOOST_FOREACH to iterate through a map?  For example, the 
following won't build:

std::map m;
BOOST_FOREACH(std::pair p, m)
{
}

I get the following error:

    warning C4002: too many actual parameters for macro 'BOOST_FOREACH'

However, the following will work OK:

std::map m;
std::pair p;
BOOST_FOREACH(p, m)
{
}

But is there a way to declare the pair within the FOREACH loop?  Note that I 
also tried the following, with no success:

std::map m;
BOOST_FOREACH(std::map::value_type p, m)
{
}

A typedef also seems to work, e.g.:
std::map m;
typedef std::pair mpair;
BOOST_FOREACH(mpair p, m)
{
}

Can the pair be declared without a typedef?  Is this a limitation of the MS 
compiler?

Thanks in advance.

Rob Caldecott

Eric Niebler

Sebastian Redl

Dave Steffen

Shunsuke Sogame

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