Which characters are replaced by matlab.lan​g.makeVali​dName?

Function matlab.lang.makeValidName does 2 things:

1. first, it checks the input string for special characters which are not allowed to be contained in identifiers and replaces those (e.g. with "")
2. second, it checks the length of the input string with possibly replaced characters, and if is too long, it truncates the string.

However, I would like the function to check only for special characters, not for length.

One option would be to use "strrep", but then I would like to generate the list of characters which are replaced by matlab.lang.makeValidName to be consistent with makeValidName.

Answer 1

[Adam Danz]

matlab.lang.makeValidName uses isvarname to determine if the string is a valid variable name. The doc page for isvarname states that a valid variable name has the following requirements

• begins with a letter
• contains not more than namelengthmax characters (run that function to return max name length)
• includes only letters, digits, and underscores.

So the regular expression to replace characters that aren't letters, digits, or underscores would be

validChars = '[^a-zA-Z_0-9]';
strClean = regexprep(str, validChars, '_')

where the caret symbol is used to match any character not contained within the character vector.

Limitations

• This does not check that the leading character is a letter.
• This does not trim leading and trailing whitespace before underscore-replacement (use strip)
• This does not remove embedded whitespace before replacement
• There are other edge cases covered by matlab.lang.makeValidName
• There are additional validity checks in matlab.lang.makeValidName

[Stephen23]

Note that '[^a-zA-Z_0-9]' can be replaced with '\W'.

[Jannik]

Such a "MetaCharacter" like '\W' was what I was looking for. Thanks to both of you! I appreciate your quick responses.