求匹配9位数字/字母、以/分三组且每组最多4位的正则表达式

Got it, let's nail this regex for you. Your requirement is straightforward: a total of 9 digits and/or letters split into three groups separated by /, with each group containing 1 to 4 characters. No more, no less.

The Working Regex #

Here's the regex that checks all your boxes:

^(?=(?:[^A-Za-z0-9]*[A-Za-z0-9]){9}[^A-Za-z0-9]*$)(?:[A-Za-z0-9]{1,4}\/){2}[A-Za-z0-9]{1,4}$

Let's Break It Down #

I’ll explain each part so you understand why it works:

• ^ and $: These anchors make sure we match the entire string—no extra characters before or after the pattern.
• (?=(?:[^A-Za-z0-9]*[A-Za-z0-9]){9}[^A-Za-z0-9]*$): This positive lookahead counts exactly 9 alphanumeric characters, ignoring the / separators. It ensures we don’t have too many or too few total characters.
• (?:[A-Za-z0-9]{1,4}\/){2}: This matches the first two groups. Each group is 1-4 alphanumeric characters followed by a /. The (?:...) is a non-capturing group (we don’t need to store each group separately unless you want to), and {2} repeats this pattern twice for the first two groups.
• [A-Za-z0-9]{1,4}: This matches the third and final group, which also has 1-4 alphanumeric characters.

Valid Examples #

These will all match the regex:

• XX/XXXX/XXX (2 + 4 + 3 = 9 total characters)
• 4444/4444/4 (4 + 4 + 1 = 9)
• ABC/DEFG/HIJ (3 + 4 + 2 = 9)
• Z/YYYY/XXXX (1 + 4 +4 =9)

Quick Adjustments #

• Case Insensitivity: If you want to allow both uppercase and lowercase letters (e.g., aBc/DeFg/HiJ), add the i flag (how you do this depends on your programming language or regex tool).
• Allow Underscores: If you ever need to include underscores (though you specified digits/letters only), replace [A-Za-z0-9] with \w (note that \w includes underscores).

内容的提问来源于stack exchange，提问作者abc def