You can use the ?for matching 0 oder once. You can use the * for 0 to infinity and plus + for once to infinity. You can put the exact number of repetitions into curly braces.
Mark the lolwhich contains exactly 8 times o.
- loool
- looooooool
- loooooooooool
For IP addresses it would have come in handy to not copy and paste the expression so often. My regular expression for IP addresses with curly braces looks like this: ^(1?\d?\d|2[0-4]\d|25[0-5])(\.(1?\d?\d|2[0-4]\d|25[0-5])){3}$
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