Regular Expression-simple memory

Many programming languages support the use of regular expressions for string matching. Regular Expressions are always a bit fuzzy. Here, we will record them and review them later.

"." Represents any character

"\ D" represents any number ranging from 0 to 9

"\ D" represents any non-Numeric Character

"\ S" represents space characters

"\ S" indicates non-space characters

"\ W" represents characters that can be used as identifiers

 

Starts with a pair of square brackets and represents any character in square brackets.

[ABC] represents any one of a B c

[^ ABC] represents any character except a B c

[A-d] represents any one of A to D

[A-d [M-p] A to D, or any one of m to P (union)

[A-Z & [DEF] represents any one of d e f (intersection)

[A-F & [^ BC] represents a d e f (difference set)

With a qualifier

X? X appears 0 this or once

X + x appears once or multiple times

X appears 0 or multiple times

X {n} X exactly appears n times

X {n,} X appears at least N times

X {n, m} X appears n to m times