问题描述：

I have a regex as follows.

\'#^(VK[1-8][0-9A-Z]+)#i\'

This is fine and will return true if the string begins with VK[1-8][0-9A-Z], for example VK2TEST. But what if, following [0-9A-Z], there is the possibility of a / and more characters, some of which I need to return true and some of which I need to return false? For example VK2TEST/P.

If I need to return, let\'s say, VK2TEST/P and VK2TEST/M as true, but other alphanumeric characters proceeding the / as false, how do I go about this? Is this even possible? For example...

VK2TEST = true
VK2TEST/P = true
VK2TEST/P1 = false
VK2TEST/M = true
VK2TEST/MM = false
VK2TEST/QRP = true

My research points me to conditional subpatterns, but I don\'t really know if I\'m heading in the right direction with this.

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感谢您的意见，我们尽快改进~

功能建议

我有一个正则表达式如下。</ p>

 \'＃^  （VK [1-8] [0-9A-Z] +）#i\'
</ code> </ pre> 
这很好，如果字符串以VK开头，则返回true [  1-8] [0-9A-Z]，例如VK2TEST。 但是，如果在[0-9A-Z]之后，有一个/更多字符的可能性</ strong>，其中一些我需要返回true，其中一些我需要返回false？ 例如VK2TEST / P.  </ p> 
如果我需要返回，让我们说，VK2TEST / P和VK2TEST / M为真，但其他字母数字字符继续/为假，我该如何处理？ 这甚至可能吗？ 例如...... </ p> 
  VK2TEST = true 
VK2TEST / P = true 
VK2TEST / P1 = false 
VK2TEST / M = true 
VK2TEST / MM = false 
VK2TEST / QRP  = true 
</ code> </ pre> 
我的研究指向条件子模式，但我真的不知道我是否正朝着正确的方向前进。</ p> 
</ div> 
网友观点：
For the following results:
VK2TEST = true
VK2TEST/P = true
VK2TEST/P1 = false
VK2TEST/M = true
VK2TEST/MM = false
VK2TEST/QRP = true
You can use a regexp like the following:
\'#^(VK[1-8][0-9A-Z]+(\\/(M|P|QRP))?)$#i\'
This syntax is covered in the PHP PCRE Meta-Character Syntax page.
Here are some tips:
\\: escape character
[]: class definition
+: one or more quantifier
?: zero or one quantifier
(): sub-pattern
|: start of alternative branch
$: end of subject
Some notes:
If you want one or more of a class, the + should be outside the class, e.g. [1-8]+ to include 11. If you want [1-8] or a +, use [1-8+]. Also, in your example [A-Z+] will match T not the extra EST characters. To match the word TEST, you can us [A-Z]+ with the + outside of the class definition.
Slashes, /, need to be escaped, hence \\/.
If you want to match different substrings you should use a sub-pattern enclosed in () while using the | branch pipe to separate patterns.
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