Php 什么是将匹配特定字符串上方所有内容的正则表达式？

什么是正则表达式，它将匹配特定字符串上方文本中的所有内容

字符串是

=====================================

，我想使用PHP获取上面的所有内容

示例文本

this is a sample text here i want to match using regex. because it is above the following line 
=============REPLY ABOVE THIS LINE=============
here is below the line

因此正则表达式将仅返回

this is a sample text here i want to match using regex. because it is above the following line 

---

为什么不这样做呢

$input = "this is a sample text here i want to match using regex. because it is above the following line =============REPLY ABOVE THIS LINE============= here is below the line"

$pieces = explode("=============REPLY ABOVE THIS LINE=============", $input);

$above_line = trim($pieces[0]);

$below_line = trim($pieces[1]);

---

@戴尔：是的，同意，很抱歉。当我得到回复时，我会将我的答案编辑成实际答案。@villoui调整了我的答案：）