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說明以下 PREG 模式有preg_filter;preg_replace;preg_grep;preg_quote;preg_match;preg_match_all;preg_split;preg_replace_callback_array

一、內部選項設置:
Internal option letters 內部選項字母
i    for PCRE_CASELESS 輕巧
m    for PCRE_MULTILINE 多線
s    for PCRE_DOTALL 點球
x    for PCRE_EXTENDED 擴展
U    for PCRE_UNGREEDY 勇氣
X    for PCRE_EXTRA 額外
J    for PCRE_INFO_JCHANGED 信息已更改

二、程式範例:
1. preg_filter:執行正則表達式搜索並替換

subject = array('1', 'a', '2', 'b', '3', 'A', 'B', '4');
result = preg_filter('/\d/', '0', subject);
print_r(result);

結果:Array ( [0] => 1 [2] => 2 [4] => 3 [7] => 4 )

2. preg_replace 用法:執行正則表達式搜索並替換,preg_replace(模式,替代,字串);

用法一:
string = 'April 15, 2003'; 
pattern = '/(\w+) (\d+), (\d+)/i';
replacement = '{1}1,3';
text = preg_replace(pattern, replacement, string);
print_r(text);

指 1=April 2=15 3=2003 {1}1=April1
結果:April1,2003

用法二:
text_1 = preg_replace('/(\w+)/i', '{1}2', string);
print_r(text_1);
結果:April2 152, 20032

用法三:如何刪除 script 之間的內容方法如下:

preg_replace("/<script.*>(.\r\n)*?<\\/script>/", "", str);

注:preg_filter 與 preg_replace 差別:
preg_filter 沒找到會空值,preg_replace 沒找到會輸出原來的值。

subject = array('1', '2', '3', 'a', 'b', 'A', 'B'); 
pattern = array('/\d/', '/[a-z]/', '/[1a]/'); 
replace = array('A:0', 'B:0', 'C:0'); 

echo "</br>preg_filter===>\n";
print_r(preg_filter(pattern, replace, subject)); 
//結果:Array ( [0] => A:C:1 [1] => A:2 [2] => A:3 [3] => B:C:a [4] => B:b )

echo "</br>preg_replace===>\n";
print_r(preg_replace(pattern, replace, subject)); 
//結果:Array ( [0] => A:C:1 [1] => A:2 [2] => A:3 [3] => B:C:a [4] => B:b [5] => A [6] => B )

3. preg_grep 用法:返回與模式匹配的數組條目

array=["123d.888","55a.555"];
fl_array = preg_grep("/(\d+)?\.\d+/", array);
print_r(fl_array);

4. preg_quote 用法:引用正則表達式字符

keywords = '50 , . g4/600';
keywords = preg_quote(keywords, '/');
echo keywords; // returns \40 for a g3\/400

5. preg_match 用法:執行正則表達式匹配

subject = "abcdef";
pattern = '/def/';
preg_match(pattern, subject, matches, PREG_OFFSET_CAPTURE);
print_r(matches);
//結果:Array ( [0] => Array ( [0] => def [1] => 3 ) )

6. preg_match_all 用法:執行全局正則表達式匹配
out[0] 保存完整模式的所有匹配 out[1]是子组的所有匹配
[>]+指 > 的開始位置,+表示一次或多次, 後面 > 指的原來的 >

preg_match_all("<[>]+>(.*)</[>]+>U","<b>example: </b><div align=left>happy to tody</div>",out,PREG_PATTERN_ORDER);
print_r(out);
/*結果:
Array ( [0] => Array ( [0] => example: [1] =>
happy to tody
) [1] => Array ( [0] => example: [1] => happy to tody ) )
*/

取得<div>到</div>之間的方法:
preg_match_all("<[>]+>(.*)</[>]+>U","<b>example: </b>
<div align=left>happy to tody</br></div>",out,PREG_PATTERN_ORDER);
print_r(out);

取得兩個不同的 <div> 與 </div>之間的內容
preg_match_all("/<div [idclass]+.*?>(.*?)<\/div>/","<div id=\"a1\">example: </div><div class=\"a1\">happy to tody</div>",out,PREG_SET_ORDER);
print_r(out);
/*結果:
Array ( [0] => Array ( [0] =>
example:
[1] => example: ) [1] => Array ( [0] =>
happy to tody
[1] => happy to tody ) )
*/

7. preg_split 用法:通過正則表達式拆解字串

空白加逗點拆解字串 => [\s,]
keywords = preg_split("/[\s,]+/", "happy day, 123");
print_r(keywords);
//結果:Array ( [0] => happy [1] => day [2] => 123 )

8. preg_replace_callback:執行正則表達式搜索並使用回調進行替換

text = "A 04/01/2004\n";
function next_year(t1){
    return (t1[1]+1);
}
echo preg_replace_callback("(\d{2})","next_year",text);
//結果:A 5/2/213

9. preg_replace_callback_array:執行正則表達式搜索並使用回調進行替換,只能 PHP 7才能使用。

subject = 'Tttttttt Ccccc';

preg_replace_callback_array(
    [
        '[a]+i' => function (match) {
            echo strlen(match[0]), ' matches for "a" found', PHP_EOL;
        },
        '[b]+i' => function (match) {
            echo strlen(match[0]), ' matches for "b" found', PHP_EOL;
        }
    ],
    subject
);

資料來源:https://www.php.net/manual/en/ref.pcre.php