RegExp (Quantifiers)

n+

Matches any string that contains at least one n

n*

Matches any string that contains zero or more occurrences of n

n?

Matches any string that contains zero or one occurrences of n

n{X}

Matches any string that contains a sequence of X n's

n{X,Y}

Matches any string that contains a sequence of X to Y n's

n{X,}

Matches any string that contains a sequence of at least X n's

n$

Matches any string with n at the end of it

^n

Matches any string with n at the beginning of it

?=n

Matches any string that is followed by a specific string n

?!n

Matches any string that is not followed by a specific string n