SET command - floating point numbers?

Question

How to use the SET command in windows for floating point arithmetic. / A stands for arithmetic, and% VAR% prints the VAR data, not the name.

For example, when I do:

SET /A VAR="2.5+3.1" ECHO %VAR% pause 

I get an error: "Missing statement". The output (5.6) should also be converted to floating point

I'm still busy learning basic syntax.

Regards, Snipe

Answer 1

The arithmetic operations of the SET / A command are performed only on 32-bit integers; however, you can easily simulate fixed-point operations with SET / A if you select the number of decimal digits and store them during operations. For instance:

 REM Select two decimal digits for all operations SET /A VAR=250+310 ECHO RESULT: %VAR:~0,-2%.%VAR:~-2% 

This method allows you to directly add or subtract two fixed-point numbers. Of course, if you want to enter numbers in the usual way (with a decimal point), you must exclude the decimal point and left zeros before performing operations.

You can also directly multiply or divide the FP number (fixed point) by an integer, and the result will be correct. To multiply or separate two FP numbers, we can use an auxiliary variable named ONE with the correct number of decimal places. For instance:

 rem Set "ONE" variable with two decimal places: SET ONE=100 rem To multiply two FP numbers, divide the result by ONE: SET /A MUL=A*B/ONE rem To divide two FP numbers, multiply the first by ONE: SET /A DIV=A*ONE/B 

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Answer 2

you cannot do this with batch.It only works with integers. But you can use Jscript or powershell:

 >powershell 5.6+3.1 8.7 

For jscript you need to create an extra bit and call it (e.g. jscalc.bat):

  @if (@x)==(@y) @end /***** jscript comment ****** @echo off cscript //E:JScript //nologo "%~f0" %* exit /b 0 @if (@x)==(@y) @end ****** end comment *********/ WScript.Echo(eval(WScript.Arguments.Item(0))); 

Example:

 >jscalc.bat "4.1+4.3" 8.4 

remember that jscript above is not very stable and will not handle a bad formatted expression.

To set the result to a variable in both cases, you will need a FOR /F wrapper:

 >for /f "delims=" %# in ('powershell 5.6+3.1') do set result=%# >set result=8.7 >for /f "delims=" %# in ('jscalc 5.6+3.1') do set result=%# >set result=8.7 

Most likely you installed powershell, but it is not available on all computers (not installed by default in Vista, XP, 2003), so if you don’t have it, you will need jscalc.bat

And also you can use jscript.net (OTHER jscript). Creating a .bat file that uses this is a bit more verbose and creates a small .exe file, but is also an option. Here is jsnetcalc.bat :

 @if (@X)==(@Y) @end /****** silent jscript comment ****** @echo off :::::::::::::::::::::::::::::::::::: ::: compile the script :::: :::::::::::::::::::::::::::::::::::: setlocal if exist "%~n0.exe" goto :skip_compilation :: searching the latest installed .net framework for /f "tokens=* delims=" %%v in ('dir /b /s /a:d /o:-n "%SystemRoot%\Microsoft.NET\Framework\v*"') do ( if exist "%%v\jsc.exe" ( rem :: the javascript.net compiler set "jsc=%%~dpsnfxv\jsc.exe" goto :break_loop ) ) echo jsc.exe not found && exit /b 0 :break_loop call %jsc% /nologo /out:"%~n0.exe" "%~f0" :::::::::::::::::::::::::::::::::::: ::: end of compilation :::: :::::::::::::::::::::::::::::::::::: :skip_compilation :: :::::::::: "%~n0.exe" %* :::::::: :: endlocal exit /b 0 ****** end of jscript comment ******/ import System; var arguments:String[] = Environment.GetCommandLineArgs(); Console.WriteLine( eval(arguments[1]) ); 

Example:

 >jsnetcalc.bat 4.5+7.8 12.3 

And another way that MSHTA uses (the expression that you want to evaluate is set in the expression):

 @echo off setlocal :: Define simple macros to support JavaScript within batch set "beginJS=mshta "javascript:close(new ActiveXObject('Scripting.FileSystemObject').GetStandardStream(1).Write(eval(" set "endJS=)));"" set "expression=8.5+3.5" :: FOR /F does not need pipe for /f %%N in ( '%beginJS% %expression% %endJS%' ) do set result=%%N echo result=%result% 

You can edit to accept arguments like the examples above ...