簡單的PHP正則表達式替換

Question

鑑於以下文字：

1. Place pastry on microwave safe plate.2. Heat on high for 3 seconds.3. Cool briefly before handling. 

我想更換一個點後面加一個點的一些（任何數量的）的所有地方。

例如，

.2. or .15. 

與

.<BR>number. 

替換爲的preg_replace模式，我目前使用的：

$pattern = "/^(\.[0-9]\.)/"; 
$replacement = ""; 

$text= preg_replace($pattern, $replacement, $text); 

如何，使用了preg_replace，替換文本，以便它把一個
之間的第一個點和數字？

Answer 1

試試這個。這裏我們使用preg_replace。

搜索：/\.(\d+)\./新增+捕獲一個以上的數字，僅用於數字改變捕獲組。

替換：.<BR>$1.$1將包含在搜索表達式中捕獲的數字。

Try this code snippet here

<?php 
ini_set('display_errors', 1); 
$string = "1. Place pastry on microwave safe plate.2. Heat on high for 3 seconds.3. Cool briefly before handling."; 
echo preg_replace("/\.(\d+)\./", ".<BR>$1.", $string); 

Answer 2

這將增加的數量和新的生產線。

在此處查看演示。 https://regex101.com/r/ktd7TW/1

$re = '/\.(\d+)\./'; //I use() to capture the number and use it in the replace as $1 
$str = '1. Place pastry on microwave safe plate.2. Heat on high for 3 seconds.3. Cool briefly before handling.'; 
$subst = '.<br>$1.'; // $1 is the number captured in pattern 

$result = preg_replace($re, $subst, $str); 

echo $result; 

Answer 3

$text = '1. Place pastry on microwave safe plate.2. Heat on high for 3 seconds.3. Cool briefly before handling.'; 
$pattern = "/(?<=\.)(?=\d+\.)/"; 
$replacement = "<br>"; 
$text= preg_replace($pattern, $replacement, $text); 
echo $text; 

輸出：

1. Place pastry on microwave safe plate.<br>2. Heat on high for 3 seconds.<br>3. Cool briefly before handling. 

說明：

/    : regex delimiter 
    (?<=\.)  : lookbehind, make sure we have a dot before 
    (?=\d+\.) : lookahead, make sure we have digits and a dot after 
/    : regex delimiter