How to For-Loop and do Math/Arithmetic Operations in Windows/NT Batch – the FizzBuzz Programming Example

The FizzBuzz is a good example to start learning a programming language – which contains the exercise of using a loop (either for-loop or a while-loop), Arithmetic operations (modulus), using a if-else condition, and finally printing to the console. You might want to exercise defining a function (containing the logics) and call/invoke it.

In Windows/NT batch command (file extension *.bat or *.cmd i.e. *.cmd indicates that the script is not for intended use on 16-bit DOS or older OS – and the *.bat indicates that the batch script can be run on all platforms), it is a bit tricky to do the Arithmetic operations. The following Batch program shows how we can do a for loop, testing if a variable is multiples of 3 or 5, and print something to the console.

@ECHO OFF
SETLOCAL ENABLEEXTENSIONS
SETLOCAL ENABLEDELAYEDEXPANSION

for /L %%i in (1,1,100) do (
    set /a mod3=%%i %% 3
    set /a mod5=%%i %% 5
    @REM mod3and5==0 if mod3 and mod5
    set /a mod3and5=!mod3! + !mod5!
    if "!mod3and5!"=="0" (
        echo FizzBuzz
    ) else (
        if "!mod3!"=="0" (
            echo Fizz
        ) else (
            if "!mod5!"=="0" (
                echo Buzz
            ) else (
                echo %%i
            )
        )
    )
)

ENDLOCAL
ENDLOCAL

SETLOCAL ENABLEDELAYEDEXPANSION allows windows/NT batch to use variables – which are noted as !variable!. The for /L %%variable(start, stop, step) is a simple for-loop that will increment the variable from start to stop with a step.

The set /a performs some Arithmetic operations where we use %% for integer modules. and finally the if something==something ( do-one-thing ) else ( do-another-thing) performs the if-else check.

Please be noted that there is no Logical AND or OR, thus it will be a bit tricky to emulate this in windows batch. You can always have nested-if checks for AND operator.

if !A!=1 (
   if !B!=2 (
     echo A=1 and B=2
   )
)

Batch File Commands

FizzBuzz:

• Sexy One-liner of Python to Solve the FizzBuzz
• How to For-Loop and do Math/Arithmetic Operations in Windows/NT Batch – the FizzBuzz Programming Example
• The FizzBuzz Example in Magik Programming Language
• GoLang: FizzBuzz

–EOF (The Ultimate Computing & Technology Blog) —