regex for matching 9-23 digits with any number of spaces or dashes inbetween

I've tried the following regex, but 开发者_JAVA百科it appears that nested "[]" are not allowed.

[\d[\s-]*]{9-23}

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You're on the right track, what you're looking for is probably:

(\d[\s-]*){8,22}\d

• a digit
• followed by any number of whitespace/dash
• 8-22 times
• followed by the final digit

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It appears that you don't want to match leading or trailing spaces and dashes, so the pattern that I think will work is:

^\d([- ]*\d){8,22}$

That is: one digit, followed by between 8 and 22 groups of zero or more dashes or spaces followed by a single digit.

Another solution which might be more obvious is this two-step solution:

1. match against \d[-\d ]+\d to make sure you have a string of digits, spaces and dashes which both begins and ends with at least one digit
2. strip out just the digits and count how many you have

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Let's try this:

([0-9][ -]*){9,23}

This regular expression is too short of an answer so here's my favorite

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For what it's worth, you might consider splitting it into two steps. In C#, for example, you could do something like this.

Regex.Match(Regex.Replace(str, "[ -]", ""), @"^\d{9,23}")

This is two string operations, so of course there may be a performance penalty if that matters to you. But it may be more readable for the next guy.