正则表达式匹配最多 9 位的整数

Question

I want to create a regular expression where only numbers are allowed with max length 9 and no minimum length. I came up with \d{9}[0-9] but it isn't working.

Answer 1

You're close. Try this:

^\d{0,9}$

The ^ and $ match the beginning and the end of the text, respectively. \d{0,9} matches anywhere in the string, so d0000 would pass because it would match the 0000 even though there is ad in it, which I don't think you want. That's why they ^$ should be in there.

Answer 2

Regular expressions can be tricky; what you've written does the following:

• \d - digit
• \d{9} - exactly 9 digits
• \d{9}[0-9] - exactly 9 digits, followed by something between 0 and 9

If you want no minimum limit of length, but a maximum length of 9, you probably want the following regular expression:

• \d{0,9} - 0 to 9 digits

Answer 3

I think It should be 1 to 9 digits:

^\d{1,9}$

Answer 4

It looks like you were close, try \d{0,9} .