用正则表达式匹配交替字母数字字符

Question

I want to match the following alphanumeric combinations using regex; ao1 a12 01p p1p 1ap 1p1 .

With the following regex I can match all but p1p and 1p1 :

[az][0-9]{1,2}|[0-9]{1,2}[az]|[az][0-9][az]|[az]{1,2}[0-9]|[0-9][az][0-9]

How do I match the alternating number/letter/number and letter/number/letter correctly using regular expressions? It needs to match precisely 3 characters, they occur within sentences.

Answer 1

You may use

(?<!\S)(?=[a-z]{0,2}\d)(?=\d{0,2}[a-z])[a-z\d]{3}(?!\S)

See the regex demo

Details

• (?<!\\S) - a whitespace or start of string should be immediately to the left of the current location
• (?=[az]{0,2}\\d) - there must be a digit after 0 to 2 letters immediately to the right of the current location
• (?=\\d{0,2}[az]) - there must be a letter after 0 to 2 digits immediately to the right of the current location
• [az\\d]{3} - three letters or digits are matched
• (?!\\S) - a whitespace or end of string should be immediately to the right of the current location.

Answer 2

Are you looking for something like below?

([\\d][a-zA-Z][\\d]|[a-zA-Z][\\d][a-zA-Z]|[a-zA-Z]{2}[\\d]|[a-zA-Z][\\d]{2}|[\\d]{2}[a-zA-Z]|[\\d][a-zA-Z]{2})

Answer 3

So if you need number/letter/number and letter/number/letter the below should work. But your input ao1 doesn't match this criteria.

\d[a-z]\d|[a-z]\d[a-z]