Re: [Boost-users] iterators and value_type in multi_array

On Fri, Aug 14, 2009 at 11:39 AM, HweeKuan Lee wrote:

i'm new to boost, but use the standard template library a lot. I have problems with the following code.

line 12: according to the reference, i should be able to do this, but cannot compile. compile error is very long, tell me if I should include them here.

my compiler: gcc version 4.0.1 (Apple Inc. build 5490)

thanks in advance for your help.

1 #include 2 3 int main ( ) { 4 5 typedef boost::multi_array matrix_type; 6 typedef matrix_type::iterator iterator; 7 8 matrix_type mat(boost::extents[2][3]); 9 double v = .2; 10 11 for(iterator it=mat.begin();it!=mat.end();++it) { 12 (*it) = v; // compile error 13 } 14 }

Your iterator dereferences to a slice through your 2-d array. To initialise all the 6 double elements of mat you need to nest another loop. #include int main ( ) { typedef boost::multi_array matrix_type; typedef matrix_type::iterator iterator; matrix_type mat(boost::extents[2][3]); double v = .2; for(iterator it=mat.begin();it!=mat.end();++it) { for(int i=0;i!=3;++i) (*it)[i] = v; } } - Rob.