[SOLVED] passing a 2D array to a function in C++

aihaike · 03-26-2012, 11:44 PM

Dear all,

I'm new in C++ and I'm trying to translate part of my code from C.
My issue that in C I have this function

Code:

void compute_energy_cuda_ (int *atom_number_p,
                           double datain[*atom_number_p][6],double h[3][3],double g[3][3],
			   double *cutoff_p,
			   double dataout[3],
			   double fx[*atom_number_p],double fy[*atom_number_p],double fz[*atom_number_p]) {
		  
  int atom_number = *atom_number_p ;
  double cutoff = *cutoff_p ; 

....

which works fine.
But when I try to compile it with g++ I get the error:

Code:

array bound is not an integer constant before ']' token

Can someone tell me how to modify this function ?

Thanks,

Éric.

velle frak · 03-27-2012, 02:36 AM

I'm no expert in C++, but I think the compiler complaints beacause it can not calculate the stack space needed during compile time, since the value of * atom_number_p is not known at compile time.

Maybe the solution is to pass the double datain 2D array as a (multiple) pointer and pass the length as an extra int argument?

Quote:

Originally Posted by aihaike

Dear all,

I'm new in C++ and I'm trying to translate part of my code from C.
My issue that in C I have this function

Code:

void compute_energy_cuda_ (int *atom_number_p,
                           double datain[*atom_number_p][6],double h[3][3],double g[3][3],
			   double *cutoff_p,
			   double dataout[3],
			   double fx[*atom_number_p],double fy[*atom_number_p],double fz[*atom_number_p]) {
		  
  int atom_number = *atom_number_p ;
  double cutoff = *cutoff_p ; 

....

which works fine.
But when I try to compile it with g++ I get the error:

Code:

array bound is not an integer constant before ']' token

Can someone tell me how to modify this function ?

Thanks,

Éric.

aihaike · 03-28-2012, 08:14 PM

Hey,

Thanks for your reply.
I figured out by just "*atom_number_p" in array declarations, like :

Code:

double datain[][6],double h[3][3],double g[3][3],
			   double *cutoff_p,
			   double dataout[3],
			   double fx[],double fy[],double fz[])