Set up code table X
chars = ['A':'Z' 'a':'z'];
for i = 1:numel(chars)
X{chars(i)} = sprintf('c%02d', i);
end
digits = '0':'9'
for i = 1:numel(digits)
X{digits(i)} = sprintf('c%02d', 59+i);
end
X{' '} = 'c22';
Encode string
s = 'My name is John, I studied Chemistry at Okawata University.';
sc = strvcat(X{'My name is John.'})
Note that you don't have to remove the punctuation marks, they are mapped to empty and removed my strvcat.
