php regular expression

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Release: 2023-03-22 22:22:01
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This article introduces regular expressions in php, and I would like to share them with you. Friends who are interested can take a look at

  • The role of regular expressions
    Split, search, match, replace string


  • ##Separator


    • Forward slash (/)

    • hash symbol (#)

    • ##Negative symbol (~)

    Universal Atom

    • ##\d
    • Decimal 0 to 9

    • \D
    • Negate decimal numbers from 0 to 9

    • \w
    • Numbers and letters underline

    • \W
    • In addition to numbers and letters underline

    • \s
    • White space characters

    • \S
    • Except whitespace characters

##metacharacters

  • .
      Matches any single character except newline characters (\n, \r)
    • *
    • Matches the previous subexpression zero or more times
    • +
    • Matches the previous subexpression one or more times
    • ?
    • Matches the previous subexpression zero or one time
    • {n}
    • n is a non Negative integer, matches a certain number of n times
    • ##{n,}

      n is a non-negative integer, matches at least n times
    • {n,m}

      m and n are both non-negative integers, where n <= m. Match at least n times and match at most m times
    • ^

      Match the beginning of the input string
    • $

      Matches the end position of the input string
    • []

      represents matching an element in a set, such as [abc] represents matching a or b or c
    • ()

      Match the content within () and get
    • ##Pattern modifier


  • i

    Case-insensitive
    • m Treat the string as multiple lines, no matter which line it is, it can match

    • s Treat the string as a single line, and the newline character is treated as an ordinary character

    • e e Use with function preg_replace() (php7 to cancel)

    • U U Only match the most recent string, no repeated matches

    • x x Ignore whitespace in the pattern

    • A Force matching from the beginning of the target string

    • D If you use $ to limit the ending character, no newline at the end is allowed

    • u The pattern string is treated as UTF-8 (can be used to match Chinese)

    • To be continued……………………
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