“[\S\s]*？” 这个正则表达式是什么意思？

Question

As far as I know,

• [\S\s] == Match Any Character,
• * == match any character
• ? == optional.

What does this means?

System.Text.RegularExpressions.Regex.Match(getMsg,"(?<=Status         :\s+)[\S\s]*?(?=  ╙█)").Value

The input that the regex is used on is:

"Status : ******** "

Answer 1

You are correct on the first assessment - [\S\s] will match any character - INCLUDING whitespaces and linebreaks. The second assessment isn't technically correct - the asterisk wildcard symbol means that it will match zero or more of the preceding token, so in combination with the first part, yes will mean 'match any character'.

? in RegEx does not mean 'optional'. It means: Makes the preceding quantifier lazy, causing it to match as few characters as possible. By default, quantifiers are greedy, and will match as many characters as possible. Makes the preceding quantifier lazy, causing it to match as few characters as possible. By default, quantifiers are greedy, and will match as many characters as possible. (Source: https://regexr.com/ ). This essentially will negate the asterisk quantifier and will mostly cause unexpected results - use '*' and '?' together with caution.

Along with the preceding \s+ token used - there is a little too much going on in this RegEx. Check out https://regexr.com/ and use this as an always tool when employing RegEx. This site not only explains every aspect of a RegEx, but also lets you test your current expression to see if a test expression matches.