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

I think [ ]{4} might work in the example where you need to detect 4 spaces. Same with the rest: [ ]{1}, [ ]{2} and [ ]{3}. If you want to detect an empty string in general, ^[ ]*$ will do.