字符类中的范围乱序 [英] Range out of order in character class

问题描述

我在preg_match()函数中遇到了这个奇怪的错误:

I'm getting this odd error in the preg_match() function:

警告:preg_match():编译失败:字符类在偏移量54处范围混乱

Warning: preg_match(): Compilation failed: range out of order in character class at offset 54

引起此问题的行是:

preg_match("/<!--GSM\sPER\sNUMBER\s-\s$gsmNumber\s-\sSTART-->(.*)<!--GSM\sPER\sNUMBER\s-\s$gsmNumber\s-\sEND-->/s", $fileData, $matches);

此正则表达式的作用是解析HTML文件，仅提取以下部分:

What this regular expression does is parse an HTML file, extracting only the part between:

<!--GSM PER NUMBER - 5550101 - START-->

和:

<!--GSM PER NUMBER - 5550101 - END-->

您是否暗示可能导致此错误的原因?

Do you have a hint about what could be causing this error?

推荐答案

如果$gsmNumber包含方括号，反斜杠或其他各种特殊字符，则可能会触发此错误.如果可能的话，您可能需要验证这一点，以确保它实际上是此点之前的数字.

If $gsmNumber contains a square bracket, backslash or various other special characters it might trigger this error. If that's possible, you might want to validate that to make sure it actually is a number before this point.

编辑2016:

有一个PHP函数可以在正则表达式中转义特殊字符: preg_quote() .

There exists a PHP function that can escape special characters inside regular expressions: preg_quote().

像这样使用它:

preg_match(
  '/<!--GSM\sPER\sNUMBER\s-\s' .
  preg_quote($gsmNumber, '/') . '\s-\sSTART-->(.*)<!--GSM\sPER\sNUMBER\s-\s' .
  preg_quote($gsmNumber, '/') . '\s-\sEND-->/s', $fileData, $matches);

很显然，在这种情况下，因为您使用了两次相同的字符串，所以可以先将带引号的版本分配给变量，然后再使用它.

Obviously in this case because you've used the same string twice you could assign the quoted version to a variable first and re-use that.

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