PHP uses regular expressions to extract characters in a string with angle brackets, parentheses, brackets, curly braces

 php uses regular expressions to extract the characters descriptor in a string with angle brackets <>, parentheses (), brackets [], curly braces {}, and a friend in need can refer to the following

&nbsp; &nbsp; Code as follows: $str = "Hello &lt; i &gt; (love) [Beijing]{Tiananmen}";&nbsp; &nbsp; echo F1 ($STR); Back to Hello &nbsp; echo f2 ($STR); Return me &nbsp; echo f3 ($STR); Back to Love &nbsp; echo f4 ($STR); Return to Beijing &nbsp; echo f5 ($STR); Back to Tiananmen &nbsp; &nbsp; function F1 ($str) &nbsp; {&nbsp; $result = Array ();&nbsp; Preg_match_all ("/^ (. *) (?:&lt;)/I", $STR, $ Result);&nbsp; return $result [1][0];&nbsp;}&nbsp; &nbsp; function F2 ($str) &nbsp; {&nbsp; $result = Array ();&nbsp; preg_m Atch_all ("/(?:&lt;) (. *) (?:&gt;)/I", $str, $result);&nbsp; return $result [1][0];&nbsp;}&nbsp; &nbsp; function F3 ($STR) &nbsp; {&nbsp; $result = Array ();&nbsp; Preg_match_all ("/(?:() (.*) (?:)) /i ", $str, $result);&nbsp; return $result [1][0];&nbsp;}&nbsp; &nbsp; function f4 ($str) &nbsp; {&nbsp; $result = Array (); &N Bsp Preg_match_all ("/(): [) (. *) (?:])/I", $str, $result);&nbsp; return $result [1][0];&nbsp;}&nbsp; &nbsp; function f5 ($STR) &nbsp; {&nbsp; $result = Array ();&nbsp; Preg_match_all ("/(?: {) (. *) (?:})/I", $str, $result);&nbsp; return $result [1][0]; &nbsp;}&nbsp; &nbsp; &nbsp; &nbsp; PS: (?: character) indicates that this character is not captured. It seems that PHP does not support converting characters to parentheses. &nbsp; Otherwise you can insert a glance around it and you can loop through it. &nbsp; PS2: Look around: (?!) (?=) (? &lt;!) (? &lt;=) &nbsp; has a less than match on the right side, no match on the left. Exclamation marks are unequal, equals numbers represent equality. &nbsp; PS3: Verified by validator, see Resources for Validator. &nbsp;