I want a regular expression for a number which is a continuous string of digits with no spaces - Please help ! Thankyou
You meant `\d`, right? Use `+` instead of `*` : `\d*` will match even and empty string.
Amarghosh
2010-01-06 09:15:07
`*` means `0 or more`, so this would match `[0-9]*` would match an empty string. Worse, given the string `abcd` this would return 5 matches: one at the start and end of the string, and one between each character. Each match would be 0-length. `+` stipulates `1 or more` and wouldn't do this.
James Polley
2010-01-06 09:16:13
+5
A:
This is the simplest:
^\d+$
This regular expression matches only sequences of one or more digits. ^ and $ mark the start and end of the string respectively.
But this would also allow numbers with leading zeros. If you don’t want that, use this:
^(0|[1-9]\d*)$
This matches either a single 0 or a number beginning with 1..9 followed by zero or more arbitrary digits.
Gumbo
2010-01-06 09:11:25
`^` and `$` mark the beginning and end of line respectively - this won't match `a123456b` because of the non-digit characters. It's not clear to me that that's what the OP was after.
James Polley
2010-01-06 09:13:13
Then again, it's not clear that it's *not* what the OP wants either.
James Polley
2010-01-06 09:23:04
+1
A:
\d+ will work in most implementations.
\d indicates digit - if your implemenation doesn't have this, use [0-9]+ instead.
+ means one or more of the preceeding pattern.
edit: Here's an example in python illustrating the difference between + and *:
>>> import re
>>> r = re.compile('[0-9]*')
>>> print r.findall('asdf')
['', '', '', '', '']
>>> r = re.compile('[0-9]+')
>>> print r.findall('asdf')
[]
>>> print r.findall('abc12345ghi')
['12345']
>>> r = re.compile('^[0-9]+$')
>>> print r.findall('abc12345ghi')
[]
James Polley
2010-01-06 09:11:49
+2
A:
If it is just for regex:
\d Matches any decimal digit; this is equivalent to the class [0-9].
So you can write
\d* or [0-9]* - from empty string to continuous string of digits
\d+ or [0-9]+ - at least one digit
If you want to know how to use this in specific language, specify the language pls.
Danail
2010-01-06 09:16:45