Introduction to PHP regular expressions /i, /is, /s, /isU, etc., regular expression isu_PHP tutorial

Introduction to PHP regular expressions /i, /is, /s, /isU, etc., regular expression isu

What are the PHP regular expressions /i, /is, /s, /isU, etc.?

i is not case sensitive

The dot metacharacter (.) in the

s pattern matches all characters, including the newline character

Whitespace characters in the

x pattern are completely ignored except those that are escaped or within a character class, # outside of an unescaped character class, and all characters between the next newline character, inclusive, Also ignored

A (PCRE_ANCHORED) If this modifier is set, the pattern is forced to be "anchored", that is, it is forced to match only from the beginning of the target string, that is, ^ is automatically added to the beginning of the pattern.

D (PCRE_DOLLAR_ENDONLY) If this modifier is set, dollar metacharacters in the pattern only match the end of the target string. Without this option, if the last character is a newline character, the dollar sign will also match before that character (but not before any other newline character). This option is ignored if the m modifier is set. There is no equivalent modifier in Perl. S When a pattern is going to be used several times, it is worth analyzing it first to speed up matching. If this modifier is set additional analysis will be performed. Currently, analyzing a pattern is only useful for non-anchored patterns that do not have a single fixed starting character.

U (PCRE_UNGREEDY) This modifier inverts the value of the number of matches so that it is not repeated by default, but becomes repeated when followed by a "?" This is not compatible with Perl. This option can also be enabled by setting the (?U) modifier in the mode.

X (PCRE_EXTRA) This modifier enables an extra feature in PCRE that is incompatible with Perl. Any backslash in the pattern followed by a letter with no special meaning results in an error, thus preserving this combination for future expansion. By default, like Perl, a backslash followed by a letter with no special meaning is treated as the letter itself. No other traits are currently controlled by this modifier. That is: greedy mode, maximum matching such as: /a[w]+?e/U matches abceade in abceadeddd instead of abce. If no U correction is added, it matches abce u (PCRE_UTF8). This modifier enables a PCRE Extra functionality that is incompatible with Perl. Pattern strings are treated as UTF-8. This modifier is available since PHP 4.1.0 under Unix and since PHP 4.2.3 under win32.

PHP regular expression problem: /<[^>]*?>*?<\/>/si This is an expression that filters all scripts. Can you explain it in detail?

Add "?" to indicate non-greedy matching...

The parameter "i" indicates to ignore case

The parameter "s" indicates that "." in the regular expression can match newlines

php regular match /href=\'([\S\s]*)\'/isU

preg_match("/href=\'([\S\s]*)\'/", $str, $match);echo $match[1]; //This is the match inside the brackets

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