squares showing upon implicit conversion from numeric to char-CodePudding

I am trying to test the behavior of adding number in an array containing a string using the following code :

warning: implicit conversion from numeric to char

I do understand the error and all, but the weird thing is that I get squares for the numbers, as in the image and I don't understand what these are

CodePudding user response：

If you want to mix heterogeneous input data in an array with Octave, you must use a cell array as container, that is, use braces instead of brackets to "concatenate" data:

>> a6 = {"test", 3, 5}
a6 =
{
  [1,1] = test
  [1,2] = 3
  [1,3] = 5
}

Otherwise, as commented by Raymond Chen, Octave tries to convert some data to make homogeneous (of the same type) their whole list.