Regular expressions in findstr

问题:

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 the 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?

回答1:

This works for me:

findstr /r "^[1-9][0-9]*$ ^-[1-9][0-9]*$ ^0$" 

If you don't use the /c option, the 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.)

回答2:

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= 

回答3:

Or if you can, download grep for windows.. Many more features than findstr provides.

回答4:

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]*$ 

回答5:

I realize this is a really old post but thought it may come up in the future so I quickly hacked out a little more advanced batch solution. Normally I would just use powershell, python, ruby or vbs. It's a lot more challenging in a batch language but why not. :-P

         @ECHO OFF         REM The _Ignore_ variable ignores text turning search if needed         SET _Ignore_=Ignore_something_if_you_need         REM Set the _Debug_ variable if you want to see all the output.         SET _Debug_=         REM Save this as a batch file and test it by passing          REM Usage:          REM Example 1:         REM IsItTextOrIsItANumberRegxExample.bat 123         REM Results:Found Number:"123"          REM Example 2:         REM IsItTextOrIsItANumberRegxExample.bat Michael123         REM Results:Found Number:"Michael123"          CALL:--CheckString %1         GOTO :Done          :--CheckString         SET __CheckString__=%~1         SET _RETURN_LETTERS_=""         SET _RETURN_NUMBERS_=""         REM Using EnableDelayedExpansion to more completely Expand the for loop results and pack in the results.          SETLOCAL ENABLEDELAYEDEXPANSION         FOR /F "tokens=1*" %%A IN ('Echo %__CheckString__%^|findstr /r "^[1-9][0-9]*$ ^-[1-9][0-9]*$ ^0$"') DO (             IF DEFINED _Debug_ ECHO Debug:%%A             If %ERRORLEVEL% EQU 0 (                 IF NOT "%%A"=="%_Ignore_%" (                     IF NOT "%%A"==" " (                         SET __ReturnNumber__=%%A                         SET __ReturnNumber__=!__ReturnNumber__: =!                     )                 )             )         )         ENDLOCAL && SET _RETURN_NUMBERS_=%__ReturnNumber__%         REM Note: SETLOCAL is used twice because sometimes variable output will add spaces when using two similar for loops.         SETLOCAL ENABLEDELAYEDEXPANSION         FOR /F "tokens=1*" %%A IN ('Echo %__CheckString__%^|findstr /r "^[a-z][A-Z]*[0-9]*"') DO (             IF DEFINED _Debug_