没有运行非字母数字字符的行的正则表达式

Question

I want to regex to match eg the below string:

Discover - CashBack Bonus & Citi TYP®

All of the non-alphanumeric characters like - , & and ® , cannot appear one after another.

Tried this: ^[A-Za-z0-9 ]+[-]*[A-Za-z0-9 ]+[&]*[A-Za-z0-9 ]+[®]*[A-Za-z0-9 ]+$

Answer 1

Tried this: ^[A-Za-z0-9 ]+[-]*[A-Za-z0-9 ]+[&]*[A-Za-z0-9 ]+[®]*[A-Za-z0-9 ]+$

This didn't match because the trailing [A-Za-z0-9 ]+$ requires 1 character of [A-Za-z0-9 ] at the end of the line, while your string ends with ® .

To match a line without runs of non-alphanumeric characters except space, you can use the regex:

^.?([A-Za-z0-9 ]++.?)*$

This is essentially

• [A-Za-z0-9 ]++ - a run of alphanumeric characters or space, followed by
• .? - at most one extra character,
• (…)* - the above occuring any number of times.

The leading ^.? is there to allow for one extra character at the start of the string. And it's important to use the possessive quantifier ++ in order to avoid catastrophic backtracking .