Cant join 2 tables with same headers. vertcat error

Can someone explain why im getting this error? Im trying to join the rows of 2 tables who have the exact same headers, but im getting an error? Online says that vertcat or [T1;T2] should do the trick no problem, but this is not the case for me. Please help

a = 
  struct with fields:
      id: 'a'
    mode: 'read'
    name: 'firstname'
    type: 'double'

>> b = a
b = 
  struct with fields:
      id: 'a'
    mode: 'read'
    name: 'firstname'
    type: 'double'

>> b.name = 'differentfirstname'
b = 
  struct with fields:
      id: 'a'
    mode: 'read'
    name: 'differentfirstname'
    type: 'double'

>> Ta = struct2table(a)
>> Tb = struct2table(b)

>> [Ta;Tb]
An error occurred when concatenating the table variable 'name'
using VERTCAT.

Caused by:
    Error using vertcat
    Dimensions of arrays being concatenated are not consistent.

Answer 1

[Adam Danz]

The error is because of a difference in character length of the two "name" fields. Vertical concatenation of characters into a character array requires the same number of characters, even in a table.

Use a cell array of characters, a string (shown below), or a category instead.

a = struct('id','a','mode','read','name',"firstname",'type','double');
%                                 string ^         ^
b = a; 
b.name = "differentfirstname";  % string, not char-vector
Ta = struct2table(a);
Tb = struct2table(b);
[Ta;Tb]

ans = 2x4 table
    id    mode            name             type 
    __    ____    ____________________    ______

    a     read    "firstname"             double
    a     read    "differentfirstname"    double