How to check if string contains some special character?

Dear all,

I have a question that the best way to check if string contains:

1. alphanumeric characters and underscore only (ex: stringabc: return 1, string abc: return 0)
2. underscore at the beginning or the end (ex: _stringabc, stringabc_ : return 0)
3. consecutive underscores (ex: string__abc : return 0)
4. numbers at the beginning (ex: 012string_abc : return 0)

Thank you so much

Answer 1

[Image Analyst]

For #1 you could use isstrprop().

For #2, see startsWith(str, '_') and endsWith(str, '_')

For #3, you can use find():

indexes = strfind(str, '__');

For #4 you could do something like

if str(1) >= '0' && str(1) <= '9'
    % str starts with a numerical digit.
else
    % str does not start with a numerical digit.
end

[galaxy]

Thank you so much

For #1 you could use isstrprop().

But alphanum option of isstrprop() function access other language character.

I want to check if string contains (a-zA-Z,0-9) and underscore(_) only.

>> str = 'あかき';
>> TF  =　isstrprop(str, 'alphanum')
TF =

  1×3 logical array

   1   1   1

[Image Analyst]

Sorry, I don't know that language. But you can always (I think) use logical comparison like

itsAChar = str(1) >= 'a && str(1) <= 'z'

where you just put in the lowest unicode character and highest unicode character instead of a and z.