How to check if a parameter (or variable) is a number in a Batch script

Question

I need to check if a parameter that is passed to a Windows Batch file is a numeric value or not. It would be good for the check to also works for variables.

I found a

Answer 1

SET "var="&for /f "delims=0123456789" %%i in ("%1") do set var=%%i
if defined var (echo %1 NOT numeric) else (echo %1 numeric)

Replace %1 with %yourvarname% as appropriate

Answer 2

You could try this. The variable passed is for example var and %var% is equal to 500.

set /a varCheck=%var%
if %varCheck% == %var% (goto :confirmed) else (exit /B)
exit /B

:confirmed
:: You can use %var% here, and it should only be executed if it is numerical!

if %var% is equal to e.g. a3453d, then it would set varCheck to be 0, and because 0 is not equal to a3453d, then it will exit batch processing.

(The exit on line 3 is just in case the if statement decides not to execute for some reason ... XD.)

Answer 3

Does the same thing as above. Have problems with special characters. However, the solution is of a different approach.

@echo off
cls
setlocal enabledelayedexpansion

if "%1"=="" (goto:eof) else (set _VAR2CHECK=%1)

for /l %%a in (0,1,9) do (
   if defined _VAR2CHECK (set "_VAR2CHECK=!_VAR2CHECK:%%a=!") else (goto :end)
)

:end
if defined _VAR2CHECK (echo %1 #NOT A VALID NUMBER) else (echo %1 #A VALID NUMBER)

set "_VAR2CHECK="
endlocal

Test scenarions:

C:\>ISNUM 1A
1A  #NOT A VALID NUMBER

C:\>ISNUM 11
11  #A VALID NUMBER

Answer 4

The easiest for positive integers should be:

IF 1%1 NEQ +1%1 echo Notnumeric!

If negative numbers (hyphen) are also to be considered, this will work

SET number=%1
if 1%1 EQU +1%1 echo positive number
if %1==-%number:-=% echo negative number

Learned from this article here

Answer 5

I use this function instead, it seems to work for me without any issues...

The Script (mytestscript.bat)

REM == Script variables =============================================
SET "NUMCODE=%1"
SET "NAME=%2"

REM == Main script ==================================================
CALL :Validate "NUMCODE"
IF ERRORLEVEL 1 EXIT /B %ERRORLEVEL%
CALL :Validate "NAME"
IF ERRORLEVEL 1 EXIT /B %ERRORLEVEL%

ECHO Validation Complete and all variables passed validation.

REM == Functions ====================================================
:IsNumeric [string-value] [return-val]
    SET "stringVal=%~1"
    SET /A numericVal=%stringVal% > nul 2> nul
    IF "%stringVal%"=="%numericVal%" (SET "%~2=1") ELSE (SET "%~2=0")
    EXIT /B 0

:Validate
    SET PASSEDVALIDATION=0

    ECHO Validating %~1...

    IF "%~1"=="NUMCODE" (
        ECHO - Value: %NUMCODE%
        IF NOT "%NUMCODE%"=="" SET PASSEDVALIDATION=1
        IF "!PASSEDVALIDATION!"=="1" (
            CALL :IsNumeric %NUMCODE% RETVAL
            SET PASSEDVALIDATION=!RETVAL!
        )
        IF "!PASSEDVALIDATION!"=="1" (
            IF NOT %NUMCODE% GEQ 1 SET PASSEDVALIDATION=0
        )
        IF "!PASSEDVALIDATION!"=="1" (
            IF NOT %NUMCODE% LEQ 526 SET PASSEDVALIDATION=0
        )
        IF "!PASSEDVALIDATION!"=="0" (
            ECHO - The first parameter is invalid, it can not be blank.
            ECHO - Valid value is a number from 1 to 526.
            ECHO - Leading zeros are not valid.
        )
    )

    IF "%~1"=="NAME" (
        ECHO - Value: %NAME%
        IF NOT "%NAME%"=="" SET PASSEDVALIDATION=1
        IF "!PASSEDVALIDATION!"=="0" (
            ECHO - The second parameter is invalid, it can not be blank.
        )
    )

    IF "!PASSEDVALIDATION!"=="0" (
        ECHO - Failed validation.
        EXIT /B 1
    ) ELSE (
        ECHO - Passed validation.
    )
    EXIT /B 0

Usage Examples:

C:\mytestscript.bat 10 MrTest
Validating NUMCODE...
- Value: 10
- Passed validation.

Validating NAME...
- Value: MrTest
- Passed validation.

C:\mytestscript.bat 600
Validating NUMCODE...
- Value: 600
- The first parameter is invalid, it can not be blank.
- Valid value is a number from 1 to 526.
- Leading zeros are not valid.
- Failed validation.

C:\mytestscript.bat 10
Validating NUMCODE...
- Value: 10
- Passed validation.

Validating NAME...
- Value: 
- The second parameter is invalid, it can not be blank.
- Failed validation.

Answer 6

Just try to divide per 1. But it doesn't work with numbers out of Z (non relative integer or decimal).

set var=29
set /a number=%var% >nul 2>&1
set /a number=%number% / 1 >nul 2>&1
if "%var%" == "%number%" (echo numeric) else (echo NOT numeric)