How to ascertain number of special characters in a string?

If there is array containing 5 different strings, how can I ascertain the number of special characters in each separate string?

Answer 1

[Jeff E]

blah = ' This line contains * some & special ( chars_!@#';
idx = regexp(blah, '_|!|\*');
special_count = size(idx, 2);

[Walter Roberson]

I would simplify the pattern to '[_!*]' instead of '_|!|\*'

If you do use [] then if you have "-" (dash, minus sign) in the list, ensure that it is either right after the "[" or right before the "[". Also if you include "^" in the list, ensure that it is not right after the "["

Answer 2

[Azzi Abdelmalek]

s={'abc/d?'  'abcd' 'Abc123\'}
out=cellfun(@numel,regexp(s,'[^a-zA-A0-9]+','match'))

[Walter Roberson]

Space is not usually considered to be a "special character". Characters in non-Roman alphabets are not usually considered to be special characters either. For example "é" would normally be considered an alphabetic character rather than a "special character".

[Azzi Abdelmalek]

s={'abc/d?'  ' abé cd' 'Abc123\'}
out=cellfun(@numel,regexp(s,'[^\w\s]+','match'))

[Walter Roberson]

\w  Any alphabetic, numeric, or underscore character. For English character sets, \w is equivalent to [a-zA-Z_0-9]

Notice that includes underscore.

Also the wording there hints that what \w matches might be locale-dependent, such as LANG=en-CA (Canadian English) perhaps having \w match something different than LANG=en-FR (Canadian French)