C＃Regex验证字符串

Question

I have the following regex pattern:

"[A-Z]{6,6}[A-Z2-9][A-NP-Z0-9]([A-Z0-9]{3,3}){0,1}"

and I want to validate a string with the following conditions

• allow only alphanumeric characters
• has length of only 8 or 11
• first 6 characters must all be uppercase letters

However, the above pattern is not working. What needs to be changed?

Answer 1

Use following regular expression:

^[A-Z]{6}[A-Za-z0-9]{2}([A-Za-z0-9]{3})?$

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First 6 characters must all be uppercase letters ( ^ means that following pattern should match at the start of the string):

^[A-Z]{6}

Now there should be 2 or 5 more alphanumeric characters; 2 alphanumeric chracters should come anyway:

[A-Za-z0-9]{2}

and 3 after that is optional ( ? : 0 or 1 match of the preceding pattern, $ means that preceding pattern should match at the end of the string):

([A-Za-z0-9]{3})?$

Using ^ and $ together ( ^PATTERN$ ), the pattern should match the whole string instead of the substring.

Answer 2

表达式应该是：

^[A-Z]{6}([A-Za-z0-9]{2}|[A-Za-z0-9]{5})$