How are MT5 two-dimensional arrays ordered?

[payne]

In computing, row-major order and column-major order describe methods for storing multidimensional arrays in linear memory.

Following standard matrix notation, rows are identified by the first index of a two-dimensional array and columns by the second index.

I declared an array as: MyArray[2][3] and loaded with simple loop *thinking* that arrays are stored in row-major order, such as MyArray[row][col];

However, in the debugger, the array appears to be in col-major order since my *watch* expression of MyArray[row][col] does not work! Instead I have to use col-major with my *watch" expression, ie, MyArray[col][row];

Can somebody please clarify the array ordering as I have not been able to fine the definitive answer in the documentation.

Thanks in advance,

payne 

[Alexey Da]

payne:

Could you explain your problem? Did you get any error?

I did small example.

[payne]

Hi Alexvd,

 It seems that using a struct as the array type is causing the issue. Note that even though the array is dimensioned as tmp[3][5], accessing the array tmp[0][4] is invalid, yet tmp[4][0] is valid and has the correct data...although it appears to be in col-major order.

 

  struct foo{
    string txt;
    int val;
  };
 
  foo tmp[3][5];
  int val;
  for(int row=0; row< ArrayRange(tmp,0); row++){
    for(int col=0; col<ArrayRange(tmp,1); col++){
      val =  10*(1+row) + (1+col);
      tmp[row][col].txt = IntegerToString(val);
      tmp[row][col].val = val;
    }
  }

 

 payne

[Ilyas]

Thank you for your message. Fixed. Please wait for updates.