MATLAB: String join does not work for char arrays

Question

I have a column list of numbers like the below

M = [2; 3; 5; 7; 16];

What I want is to create a string array like this

"2, 3, 5, 7, 16"

Why can't I use the below to get what I want? What is the correct way to do this?

b = join(num2str(M), ', ')

Here is the error:

"First argument must be a string array, character vector, or cell array of character vectors."

Answer 1

One approach:

M = [2; 3; 5; 7; 16];
M2Str = sprintf("%d, ",M(1:end-1)) + string(M(end))

producing:

M2Str = 
    "2, 3, 5, 7, 16"

.