Regular expressions in findstr
I'm doing a little string validation with findstr
and its /r
flag to allow for regular expressions. In particular I'd like to validate integers.
The regex
^[0-9][0-9]*$
worked fine for non-negative numbers but since I now support negative numbers as well I tried
^([1-9][0-9]*|0|-[1-9][0-9]*)$
for either positive or negative integers or zero.
The regex works fine theoretically. I tested it in PowerShell and it matches what I want. However, with
findstr /r /c:"^([1-9][0-9]*|0|-[1-9][0-9]*)$"
it doesn't.
While I know that findstr
doesn't have th开发者_Python百科e most advanced regex support (even below Notepad++ which is probably quite an achievement), I would have expected such simple expressions to work.
Any ideas what I'm doing wrong here?
This works for me:
findstr /r "^[1-9][0-9]*$ ^-[1-9][0-9]*$ ^0$"
If you don't use the /c
option, the <Strings>
argument is treated as a space-separated list of search strings, which makes the space a sort of crude replacement for the |
construct. (As long as your regexes don't contain spaces, that is.)
Argh, I should have read the documentation better. findstr
apparently doesn't support alternations (|
).
So I'm probably back to multiple invocations or replacing the whole thing with a custom parser eventually.
This is what I do for now:
set ERROR=1
rem Test for zero
echo %1|findstr /r /c:"^0$">nul 2>&1
if not errorlevel 1 set ERROR=
rem Test for positive numbers
echo %1|findstr /r /c:"^[1-9][0-9]*$">nul 2>&1
if not errorlevel 1 set ERROR=
rem Test for negative numbers
echo %1|findstr /r /c:"^-[1-9][0-9]*$">nul 2>&1
if not errorlevel 1 set ERROR=
Or if you can, download grep for windows.. Many more features than findstr
provides.
A simpler regex
that achieves the same thing is possible, just add an optional minus to the start of your original expression:
^-?[0-9][0-9]*$
Support for regex in findstr is quite limited. I suggest using Notepad++. The find in files option supports Perl Compatible Regular Expressions; results showing filename, line number and matching text can be easily copied to a text file.
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