How to select non-string variables convertvars( ) argument?

I want to convert non-string variables to string using convertvars. I can do convertvars(T, @isnumeric, 'string') and convertvars(T, @iscell, 'string'). When I want to convert all variables to string, that approach would be cumbersome. I have tried ~@isstring. That is of course a rediculous and wrong idea. Is there a way to select non-string variables from a table?

c = {1,2,3;'a','b','c'; "d", "e", "f"}'

c = 3×3 cell array
    {[1]}    {'a'}    {["d"]}
    {[2]}    {'b'}    {["e"]}
    {[3]}    {'c'}    {["f"]}

t = cell2table(c)

t = 3×3 table
    c1     c2      c3 
    __    _____    ___

    1     {'a'}    "d"
    2     {'b'}    "e"
    3     {'c'}    "f"

convertvars(t, @isnumeric, 'string') % convert one column at a time

ans = 3×3 table
    c1      c2      c3 
    ___    _____    ___

    "1"    {'a'}    "d"
    "2"    {'b'}    "e"
    "3"    {'c'}    "f"

convertvars(t, 1:width(t), 'string') % works but I like to see a better solution

ans = 3×3 table
    c1     c2     c3 
    ___    ___    ___

    "1"    "a"    "d"
    "2"    "b"    "e"
    "3"    "c"    "f"

[Mathieu NOE]

why is

convertvars(t, 1:width(t), 'string') % works but I like to see a better solution

not a good solution in your eyes ?

[Simon]

load patients.mat
t=table(Age, Location, LastName, Gender, Height);

This solution is slower because it converts string to string reduntly.

tic
convertvars(t, 1:width(t), 'string');
toc

Elapsed time is 0.016945 seconds.

Much faster solution

tic 
convertvars(t, @(x)~isstring(x), 'string');
toc

Elapsed time is 0.004329 seconds.

Answer 1

[Voss]

c = {1,2,3;'a','b','c'; "d", "e", "f"}'

c = 3×3 cell array
    {[1]}    {'a'}    {["d"]}
    {[2]}    {'b'}    {["e"]}
    {[3]}    {'c'}    {["f"]}

t = cell2table(c)

t = 3×3 table
    c1     c2      c3 
    __    _____    ___

    1     {'a'}    "d"
    2     {'b'}    "e"
    3     {'c'}    "f"

convertvars(t, @(x)~isstring(x), 'string')

ans = 3×3 table
    c1     c2     c3 
    ___    ___    ___

    "1"    "a"    "d"
    "2"    "b"    "e"
    "3"    "c"    "f"