59 lines
1.7 KiB
Batchfile
59 lines
1.7 KiB
Batchfile
::Long Multiplication Task from Rosetta Code
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::Batch File Implementation
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@echo off
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call :longmul 18446744073709551616 18446744073709551616 answer
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echo(%answer%
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exit /b 0
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rem The Hellish Procedure
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rem Syntax: call :longmul <n1> <n2> <variable to store product>
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:longmul
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setlocal enabledelayedexpansion
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rem Define variables
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set "num1=%1"
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set "num2=%2"
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set "limit1=-1"
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set "limit2=-1"
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set "length=0"
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set "prod="
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rem Reverse the digits of each factor
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for %%A in (1,2) do (
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for /l %%B in (0,1,9) do set "num%%A=!num%%A:%%B=%%B !"
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for %%C in (!num%%A!) do ( set /a limit%%A+=1 & set "rev%%A=%%C!rev%%A!" )
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)
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rem Do the multiplication
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for /l %%A in (0,1,%limit1%) do (
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for /l %%B in (0,1,%limit2%) do (
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set /a iter=%%A+%%B
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set /a iternext=iter+1
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set /a iternext2=iter+2
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set /a prev=digit!iter!
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set /a digit!iter!=!rev1:~%%A,1!*!rev2:~%%B,1!
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rem The next line updates the length of "digits"
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if !iternext! gtr !length! set length=!iternext!
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if !iter! lss !length! set /a digit!iter!+=prev
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set /a currdigit=digit!iter!
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if !currDigit! gtr 9 (
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set /a prev=digit!iternext!
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set /a digit!iternext!=currdigit/10
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set /a digit!iter!=currdigit%%10
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rem The next line updates the length of "digits"
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if !iternext2! gtr !length! set length=!iternext2!
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if !iternext! lss !length! set /a digit!iternext!+=prev
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)
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)
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)
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rem Finalize product reversing the digits
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for /l %%F in (0,1,%length%) do set "prod=!digit%%F!!prod!"
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endlocal & set "%3=%prod%"
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goto :eof
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