.NET Regex to match repeated character

Question

I'm trying to use .NET regular expressions to detect cases where a string has 5 or more characters and the only character in the string is the same. So these would be seen as matches:

0000000000000

ZZZZZZZZZ

AAAAAA

But these wouldn't:

000000A000000

ZZZZZZ ZZZ Z

AA

Is there a regular expression that could detect this pattern?

It is easy with `^(.)\1{4}$` – Wiktor Stribiżew Jun 22 '16 at 17:15 — Wiktor Stribiżew, Jun 22 '16 at 17:15

score 3 · Answer 1 · edited Jul 17 '16 at 21:03

Wiktor was close, but his will only match exactly 5 characters. Sounds like you want 5 or more. So what I'd use is

^(.)\1{4,}$

The (.)\1 will capture exactly one character. The {4,} specifies that the one character is then repeated 4 or more times. Wrapping it all in ^ and $ means the string starts immediately before that and ends immediately after, so nothing else is allowed to come before or after it.

.NET Regex to match repeated character

1 Answers1