正則表達式 · 知識管理

正則表達式的功能只要就是搜索和替換 php 的正則表達式的函數有這些: # 搜索 ## preg_match ```php >>> $pattern = '/^a\w+f$/'; => "/^a\w+f$/" >>> $subject = 'adfgf'; => "adfgf" >>> preg_match($pattern, $subject,$matches); => 1 >>> $matches => [ "adfgf", ] >>> $subject = 'adfd'; => "adfd" >>> preg_match($pattern, $subject,$matches); => 0 >>> $matches => [] ``` ## preg_match_all 一個全局正則表達式匹配 ```php >>> preg_match_all("/a\d+/", 'a4,a64', $matches); => 2 >>> $matches => [ [ "a4", "a64", ], ] >>> preg_match("/a\d+/", 'a4,a64', $matches); => 1 >>> $matches => [ "a4", ] ``` ## preg_split 通過一個正則表達式分隔字符串 ```php >>> preg_split('/\d+/', 'l12d45f55addd') => [ "l", "d", "f", "addd", ] >>> preg_split('|[a-z]+|', 'l12d45f55addd') => [ "", "12", "45", "55", "", ] ``` ## preg_grep ?返回匹配的數組 ```php >>> preg_grep("/^(\d+)?\.\d+$/", ['12.3','56.2','45','ll']) => [ "12.3", "56.2", ] ``` 功能上和array_filter很像 # 替換 ## preg_replace/preg_filter 這兩個函數功能基本一樣, 區別在底部 ```php >>> preg_replace('/sb/', '*', 'u are a sb') => "u are a *" // 這不就是關鍵字屏蔽么 >>> preg_filter('/sb/', '*', 'u are a sb') => "u are a *" >>> $content = "Name: {Name}\nEmail: {Email}\nAddress: {Address}\n"; => """ Name: {Name}\n Email: {Email}\n Address: {Address}\n """ >>> $patterns = ["/{Name}/", "/{Email}/", "/{Address}/"]; => [ "/{Name}/", "/{Email}/", "/{Address}/", ] >>> $replace = ["Jaime", "xsu@viewtool.com", "Chongqing China"]; => [ "Jaime", "xsu@viewtool.com", "Chongqing China", ] >>> echo preg_replace($patterns, $replace, $content); Name: Jaime Email: xsu@viewtool.com Address: Chongqing China => null >>> echo preg_filter($patterns, $replace, $content); Name: Jaime Email: xsu@viewtool.com Address: Chongqing China => null // 修改內容為數組 >>> $content = ['{Name}', '{Email}', 'Address', '{Address}' ] => [ "{Name}", "{Email}", "Address", "{Address}", ] >>> print_r(preg_replace($patterns, $replace, $content)) Array ( [0] => Jaime [1] => xsu@viewtool.com [2] => Address [3] => Chongqing China ) => true >>> print_r(preg_filter($patterns, $replace, $content)) Array ( [0] => Jaime [1] => xsu@viewtool.com [3] => Chongqing China ) => true ``` ## preg_replace_callback ```php <?php $content = "end 1992-01-27\n"; $content.= "start 2007-08-30\n"; $pattern = '/\d{4}(-\d{2}){2}/'; // 回調函數, 把時間換成時間戳 function time_to_ts($matches) { var_dump($matches); return strtotime($matches[0]); } echo preg_replace_callback($pattern, "time_to_ts", $content); ``` 結果 ```shell $ php index.php array(2) { [0] => string(10) "1992-01-27" [1] => string(3) "-27" } array(2) { [0] => string(10) "2007-08-30" [1] => string(3) "-30" } end 696441600 start 1188403200 ``` ## preg_replace_callback_array 這個沒用過, 用的時候加上 # 輔助函數 ## preg_quote 正則表達式特殊字符(*. \ + \* ? [ ^ ] $ ( ) { } = ! < > | : -)加上轉義的斜線 ```php >>> preg_quote('. \ + * ? [ ^ ] $ ( ) { } = ! < > | : -') => "\. \\ \+ \* \? \[ \^ \] \$  \{ \} \= \! \< \> \| \: \-" ``` ## preg_last_error 獲取最后一次正則表達式的錯誤用法遠不止這些, 更多的請看文檔, 我這里只是寫了我用到的 * [正則表達式語法](http://php.net/manual/zh/reference.pcre.pattern.syntax.php) * [正則表達式文檔](http://php.net/manual/zh/ref.pcre.php)