Question

There is a function, accepting 2D-array:

void foo ( double ** p ) 
{ /*writing some data into p*/ }

I wouldn’t like to pass raw 2D array into this function because i don’t want to manage memory calling new and delete. Also i wouldn’t like to change function signature to void foo ( std::vector< std::vector<double> >& ). And i can’t make foo as a template function (in my project it’s a COM-interface method).

I would like to pass some RAII object decoring it raw-one, like

void foo ( double * p ){}
std::vectore<double> v(10);
p( &v[0] );

Is there way to do this for 2D-arrays? I tried

std::vector< std::vector<int> > v;
foo( &v[0][0] )

and

std::vector< std::tr1::shared_ptr<int> > v;

but i get compile errors error C2664 - cannot convert parameter.

Also, can one be sure that raw address arithmetics inside the function works ok in this case?

No C++11, the sizes of 2D-array are known.

Answer 1

One possible solution is to change:

std::vector< std::vector<int> > v;
foo( &v[0][0] )

to

std::vector< std::vector<int> > v;
std::vector<int*> v_ptr;
for (...) {
    v_ptr[i] = &v[i][0];
}
foo( &v_ptr[0])