Floating point division in a dos batch

Question

Hi need to do a floating-point division in a dos batch.

I didn't find a way to do it. Something like this :

SET /A Res=10/3

returns a integer number.

Is it possible to do it ?

Answer 1

Batch files as such do not support the floating point arithmetic. However, this article suggests a workaround that uses an external script file to do calculations. The script file should use some sort of eval function to evaluate the expression passed as an argument and return the result. Here's a sample VBScript file (eval.vbs) that does this:

WScript.Echo Eval(WScript.Arguments(0))

You can call this external script from your batch file, specify the expression to be evaluated and get the result back. For example:

@echo off
for /f %%n in ('cscript //nologo eval.vbs "10/3"') do (
  set res=%%n
)
echo %res%

Of course, you'll get the result as a string, but it's better than nothing anyway, and you can pass the obtained result to the eval script as part of another expression.

Answer 2

According to this reference, there is no floating point type in DOS batch language:

Although variables do exist in the DOS batch programming language, they are extremely limited. There are no integer, pointer or floating point variable types, only strings.

I think what you are trying to do will be impossible without implementing your own division scheme to calculate the remainder explicitly.