regular expression for anything but an empty string

Question

Is it possible to use a regular expression to detect anything that is NOT an \"empty string\" like this:

string s1 = \"\";
string s2 = \" \";
string s3 = \"          


        

Answer 1

You can do one of two things:

• match against ^\s*$; a match means the string is "empty"
  • ^, $ are the beginning and end of string anchors respectively
  • \s is a whitespace character
  • * is zero-or-more repetition of
• find a \S; an occurrence means the string is NOT "empty"
  • \S is the negated version of \s (note the case difference)
  • \S therefore matches any non-whitespace character

References

• regular-expressions.info, Anchors, Repetition
• MSDN - Character classes - Whitespace character \s
  • Note that unless you're using RegexOptions.ECMAScript, \s matches things like ellipsis …

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