replace spaces in a string

Im doing a practice question and I got the question:

Replace any occurrence of two or more consecutive blank spaces with one (single) blank space

I attempted it a bunch of ways but so far the code Ive got is:

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

C = 0;
for i=1:n
    if str(i) == ' '
        C = C+1;
        blankpos(C) = i;
    end
end
fprintf('Position of the blank spaces: \n');
blankpos

C1 = 0;
strm=str;

for i=1:n
    if str == '   '
        C1 = C1+1;
        posreplace(C1)=i;
        if str == '  '
            C1 = C1+1;
            posreplace(C1)=i;
        end
    end
end

strm(posreplace) = ' ';
fprintf('The modified string: ');
strm

Answer 1

[Walter Roberson]

str = regexprep(str, ' +', ' ');

[nagendra badiger]

Really elegant solution

Answer 2

[Image Analyst]

One way is to use strrep():

s = 'a  a    a      a'  % Test string.
% Repeatedly loop replacing double spaces by single space
% until there are no double spaces left.
while contains(s, '  ')
  s = strrep(s, '  ', ' ');
end
s % Display in command window.

[Mitul Dattani]

what if there are triple spaces thats hats tripping me up as in the question im given theres a triple space

[Image Analyst]

Did you try it? It works with any number of spaces.

However, Walter's answer looks like the best answer to me.

Answer 3

[Jan]

With https://www.mathworks.com/matlabcentral/fileexchange/41813-runlength:

s      = 'a  a    a      a b bcd a  ';
[B, N] = RunLength(s);
N(B == ' ') = 1;
s      = RunLength(B, N);