Randomize a string from input

From a past paper theres a question that asks for a string, then the blank spaces, then the first word, the to randomize the first word. I managed to do all of it except randomize the last word. I've put my code below not exactly too sure what to put here, pretty sure what I've put is wrong.

str=input('Give a string: ')
[m, n] = size(str);

C = 0;
for i = 1:n
    if str(i) == ' '
        C=C+1;;
        pos_blanks(C) = i;
    end
end
pos_blanks

first_word = str(1:pos_blanks(1)-1);
first_word

perm_of_first_word = randi(first_word);
perm_of_first_word

Answer 1

[Roger Stafford]

To obtain a random permutation of 'first_word' you need the 'randperm' function, not 'randi':

   perm_of_first_word = first_word(randperm(length(first_word)));

[Mitul Dattani]

Wicked thankyou! I'm so silly aha

[Roger Stafford]

@Mitul Dattani: Here is how you can do the whole problem, which, as I understand it, is to randomly permute the characters within each of the "words" in a given input string:

str = input('Give a string: ');
pstr = str; % pstr will receive the permuted result
d = diff([false,str~=' ',false]); % For comparing successive characters
f1 = find(d>0); % Indices of first character in each word
f2 = find(d<0)-1; % Indices of final character in each word
for k = 1:length(f1) % Loop once for each word
  w = str(f1(k):f2(k)); % Get the k-th word
  pstr(f1(k):f2(k)) = w(randperm(f2(k)-f1(k)+1)); % Randomly permute its characters
end