Question

Why isn’t this regex working for the string “Array a”?

let mutable line = "Array a"
let regexIdentifier = new Regex("^[a-zA-Z_][a-zA-Z0-9_]*$")   
line <- regexIdentifier.Replace(line, "\r\n$&\r\n")   //KEYWORDS separation
Console.WriteLine(line)   

(I want the program to separate both “Array” and “a” to different lines)

Answer 1

This pattern separate the “Array a” in two distinct matches

string rPattern = @"\b[A-Za-z_][A-Za-z_0-9]+\b";

works also for a string like

"Exam_ple1 a9"

• The \b limits the pattern at the word boundaries. (this gives back
  two Matches for the input text also if you have more than one space between)
• The first character should be from the ranges A-Za-z or an underscore (not numbers).
• The following characters should be from the ranges A-Za-z0-9 or an underscore.