How to use random in BATCH script?

How to use random in BATCH script?

Solution 1:

%RANDOM% gives you a random number between 0 and 32767.

Using an expression like SET /A test=%RANDOM% * 100 / 32768 + 1, you can change the range to anything you like (here the range is [1…100] instead of [0…32767]).

Solution 2:

%RANDOM% gives you a random number between 0 and 32767.

You can control the number's range with:

set /a num=%random% %%100

- will produce number between 0~99.

This one:

set /a num=%random% %%100 +1

- will produce number between 1~100.

Solution 3:

You'll probably want to get several random numbers, and may want to be able to specify a different range for each one, so you should define a function. In my example, I generate numbers from 25 through 30 with call:rand 25 30. And the result is in RAND_NUM after that function exits.

@echo off & setlocal EnableDelayedExpansion

for /L %%a in (1 1 10) do (
        call:rand 25 30
        echo !RAND_NUM!
)

goto:EOF

REM The script ends at the above goto:EOF.  The following are functions.

REM rand()
REM Input: %1 is min, %2 is max.
REM Output: RAND_NUM is set to a random number from min through max.
:rand
SET /A RAND_NUM=%RANDOM% * (%2 - %1 + 1) / 32768 + %1
goto:EOF

Solution 4:

@echo off & setLocal EnableDelayedExpansion

for /L %%a in (1 1 100) do (
echo !random!
)