PHP:RegEx用于3-9个字母和5-50个数字的字符串 [英] PHP: RegEx for string with 3-9 letters and 5-50 numbers

问题描述

如何在PHP中制作仅接受3-9个字母(大写)和5-50个数字的RegEx?

How can I make a RegEx in PHP that only accepts 3-9 letters (uppercase) and 5-50 numbers?

我不太擅长正则表达式.但这不起作用:

I'm not that good at regular expressions. But this one doesn't work:

/[A-Z]{3,9}[0-9]{5,50}/

例如，它匹配ABC12345，但不匹配A12345BC

For instance, it matches ABC12345 but not A12345BC

有什么想法吗?

推荐答案

这是经典的密码验证"类型的问题.为此，粗略配方"是先检查每个条件，然后我们进行匹配.

This is a classic "password validation"-type problem. For this, the "rough recipe" is to check each condition with a lookahead, then we match everything.

^(?=(?:[^A-Z]*[A-Z]){3,9}[^A-Z]*$)(?=(?:[^0-9]*[0-9]){5,50}[^0-9]*$)[A-Z0-9]*$

我将在下面说明这一点，但是这里有一个变体，请您找出.

I'll explain this one below, but here's a variation that I'll leave for you to figure out.

^(?=(?:[^A-Z]*[A-Z]){3,9}[0-9]*$)(?=(?:[^0-9]*[0-9]){5,50}[A-Z]*$).*$

让我们逐个看一下正则表达式.

Let's look at the first regex piece by piece.

1. 我们将正则表达式锚定在字符串^的头部和字符串$断言的末尾之间，以确保匹配项(如果有)是整个字符串.
2. 我们有两种先行方式:一种是大写字母，一种是数字.
3. 先行查找后，[A-Z0-9]*匹配整个字符串(如果它仅包含大写ASCII字母和数字). (感谢@TimPietzcker指出我在车轮上从星点开始时睡着了.)

1. We anchor the regex between the head of string ^ and end of string $ assertions, ensuring that the match (if any) is the whole string.
2. We have two lookaheads: one for the capital letters, one for the digits.
3. After the lookaheads, [A-Z0-9]* matches the whole string (if it consists only of uppercase ASCII letters and digits). (Thanks to @TimPietzcker for pointing out that I was asleep at the wheel for starting out with a dot-star there.)

提前行如何工作?

(?:[^A-Z]*[A-Z]){3,9}[^A-Z]*$)断言，在当前位置(即字符串的开头)，我们可以匹配任意数量的不是大写字母的字符，后跟一个大写字母"，匹配3到9次.这样可以确保我们有足够的大写字母.请注意，{3,9}是贪婪的，因此我们将匹配尽可能多的大写字母.但是我们不希望匹配超过我们希望的范围，因此在表达式用{3,9}进行量化之后，先行检查是否可以匹配不是大写字母的零个或任意个数"的字符，直到最后的字符串，由锚点$标记.

The (?:[^A-Z]*[A-Z]){3,9}[^A-Z]*$) asserts that at the current position, i.e. the beginning of the string, we are able to match "any number of characters that are not capital letters, followed by a single capital letter", 3 to 9 times. This ensures we have enough capital letters. Note that the {3,9} is greedy, so we will match as many capital letters as possible. But we don't want to match more than we wish to allow, so after the expression quantifies by {3,9}, the lookahead checks that we can match "zero or any number" of characters that are not a capital letter, until the end of the string, marked by the anchor $.

第二个超前工作方式相似.

The second lookahead works in similar fashion.

有关此技术的更深入说明，您可能需要仔细阅读此页面的密码验证部分，其中有关正则表达式环顾.

For a more in-depth explanation of this technique, you may want to peruse the password validation section of this page about regex lookarounds.

如果您有兴趣，这里是该技术的逐个令牌说明.

In case you are interested, here is a token-by-token explanation of the technique.

^                      the beginning of the string
(?=                    look ahead to see if there is:
 (?:                   group, but do not capture (between 3 and 9 times)
  [^A-Z]*              any character except: 'A' to 'Z' (0 or more times)
   [A-Z]               any character of: 'A' to 'Z'
 ){3,9}                end of grouping
  [^A-Z]*              any character except: 'A' to 'Z' (0 or more times)
$                      before an optional \n, and the end of the string
)                      end of look-ahead
(?=                    look ahead to see if there is:
 (?:                   group, but do not capture (between 5 and 50 times)
  [^0-9]*              any character except: '0' to '9' (0 or more times)
   [0-9]               any character of: '0' to '9'
 ){5,50}               end of grouping
  [^0-9]*              any character except: '0' to '9' (0 or more times)
$                      before an optional \n, and the end of the string
)                      end of look-ahead
[A-Z0-9]*              any character of: 'A' to 'Z', '0' to '9' (0 or more times)
$                      before an optional \n, and the end of the string

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