Regular expression maximum occurrences

[DarwinIT]

Regex testExp = new Regex("[0-9a-zA-Z]{3,6}");
MessageBox.Show(testExp.IsMatch(txtIDS.Text).ToString());

From what I read - this regular expression should return True as long as I have an alpha numeric string of 3 to 6 characters. The minimum quantifier works but the maximum is not since it returns true with 7, 8, 9 etc. characters. Am I doing something wrong? Or perhaps C# doesn't support this ??

 

[tsuji]

If you want max 6 no longer exists anywhere in the string to match, add a negative lookahead.
[tt] Regex testExp = new Regex("[0-9a-zA-Z]{3,6}[blue](?![0-9a-zA-Z])")[/blue];[/tt]

 

[tsuji]

Further note:
... and then the lower limit needs enforcement too. Hence the complete pattern should read like this.
[tt] Regex testExp = new Regex("[blue](?<![0-9a-zA-Z])[/blue][0-9a-zA-Z]{3,6}[blue](?![0-9a-zA-Z])[/blue]");[/tt]

 

[NESWalt]

Why not just do the following?

Regex testExp = new Regex("^[0-9a-zA-Z]{3,6}$");

From the post, I'm assuming that non alpha-numeric characters are allowed.

 

[DarwinIT]

Neswalt has the best answer. Needed the ^ to preface the expression and the $ at the end. I didn't want non-alphanumerics so added a @ in front of the whole expression and now it works. Thanks!!!