c++ - How to pass two-dimensional array as an argument?

Question

My Matrx class is defined as

class Matrx
{
 double A[50][50];
 int m,n;
public:
 Matrx(void);
 Matrx(int a, int b)
 {
  m=a;
  n=b;
 }
 Matrx operator +(Matrx b);
 Matrx Transpose(Matrx b);
 Matrx operator *(Matrx b);
 CString printMatrx();
 void readMatrx(double a[][]);
 Matrx TransposeMat(Matrx b);
};

void Matrx::readMatrx(double a[][])
{
 for(int i=0;i< m;i++)
  {
   for(int j=0;j< n;j++)
    A[i][j]=a[i][j];
  }
}

The intellisense gives error like the below

1 IntelliSense: an array may not have elements of this type d:madaptive_dd_v1.02matrx.h 17 27 TestServer

Why?

How to pass a two dimensional array as argument of the function?

Answer 1

The problem is that when passing multidimensional arrays as parameters in C++, you must specify the dimension of the outermost array. For example:

void ThisIsIllegal(int arr[][]); // Wrong!
void ThisIsAlsoIllegal(int arr[10][]); // Also wrong
void ThisIsLegal(int arr[][10]); // Okay

If you want to be able to have a function that takes in an array of any size, you can use templates:

template <size_t N, size_t M>
void ThisIsAlsoLegal(int (&arr)[M][N]);

This last version accepts any multidimensional array of the right type, and is probably what you're looking for.