Julia 1.8.2 message ERROR: LoadError: too many parameters for type

New to Julia
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1

Hi! The header file (.h) of a C shared library contains the following declaration:

typedef struct {
  int path;			/**< MISR path number */
  long long projcode;		/**< GCTP projection code */
  long long zonecode;		/**< GCTP zone code */
  long long spherecode;		/**< GCTP sphere code */
  double projparam[15];		/**< GCTP projection parameters */
  double ulc[2];		/**< MISR ulc_xy of first block */
  double lrc[2];		/**< MISR lrc_xy of first block */
  int nblock;			/**< MISR number blocks */
  int nline;			/**< MISR number lines */
  int nsample;			/**< MISR number samples */
  float reloffset[179];		/**< MISR relative block offset */
  int resolution;		/**< MISR resolution */
} MTKt_MisrProjParam;

which I have translated into

struct MTKt_MisrProjParam
    path::Cint
    projcode::Clonglong
    zonecode::Clonglong
    spherecode::Clonglong
    projparam::Vector{15, Cdouble}
    ulc::Vector{2, Cdouble}
    lrc::Vector{2, Cdouble}
    nblock::Cint
    nline::Cint
    nsample::Cint
    reloffset::Vector{179, Cfloat}
    resolution::Cint
end

However, each time I try to use the module containing that declaration, I get the error message

ERROR: LoadError: too many parameters for type

This error comes from anyone of the 4 lines containing Vector because commenting them out removes the error. So what should the correct syntax be to include a vector in a struct? Thanks for suggestions.

2

Vector only accept one parameter which is the type of the element. So it should be Vector{T}. The struct below can work

struct MTKt_MisrProjParam
           path::Cint
           projcode::Clonglong
           zonecode::Clonglong
           spherecode::Clonglong
           projparam::Vector{Cdouble}
           ulc::Vector{Cdouble}
           lrc::Vector{Cdouble}
           nblock::Cint
           nline::Cint
           nsample::Cint
           reloffset::Vector{Cfloat}
           resolution::Cint
       end
3

You should use a static vector for this purpose. A Vector will only place a pointer in the julia struct, whereas the vector itself will be on the heap. Either an SVector or an MVector:

using StaticArrays
struct ...
   path::Cint
   ...
   projparam::SVector{15, Cdouble}
   ...
end
4

@yusri-dh and @sgaure: Thank you both for these valuable inputs. I knew of Vector but not SVector, so thanks for introducing me to that package.

5

But heed the warnings mentioned in StaticArrays.jl’s readme about vector length. With 179 elements your field reloffset is likely too long for a SVector to be performant.