Can I make a negative value in batch display as 0? - batch-file

Question

I am coding a store generator for a table top RPG. I have it set up to generate different content based on which faction you select, a random roll to determine how well the shop is doing (poor, average, good, excellent), and then randomly determines the amount of an item in the shop.
However to make certain items more or less likely to show up I set it to have say 3d6-5 Arrows, this results in a minimum of -2 and a maximum of 13 arrows. Naturally a store cannot have -2 arrows. Is there any way to be able to still set a minimum and maximum range for a variable, but have 0 be the lowest, or make any negative value display as 0?

Answer 1

if %val% lss 0 set /a val=0
is one way
Here's a more comprehensive version:
#ECHO OFF
SETLOCAL
SET val=5
ECHO ==== :setlt =====
CALL :setlt val 3&CALL :showval %val% val
CALL :setlt val 6&CALL :showval %val% val
CALL :setlt val 5&CALL :showval %val% val
CALL :setlt val 3 27&CALL :showval %val% val
CALL :setlt val 6 1&CALL :showval %val% val
CALL :setlt val 5 11&CALL :showval %val% val
ECHO ==== :setgt =====
CALL :setgt val 3&CALL :showval %val% val
CALL :setgt val 6&CALL :showval %val% val
CALL :setgt val 5&CALL :showval %val% val
CALL :setgt val 3 27&CALL :showval %val% val
CALL :setgt val 6 1&CALL :showval %val% val
CALL :setgt val 5 11&CALL :showval %val% val
ECHO ==== :setra =====
CALL :setra val 3 8&CALL :showval %val% val
CALL :setra val 8 11&CALL :showval %val% val
CALL :setra val 2 4&CALL :showval %val% val
CALL :setra val 3 8 6&CALL :showval %val% val
CALL :setra val 8 11 6&CALL :showval %val% val
CALL :setra val 2 4 6&CALL :showval %val% val
CALL :setra val 3 8 6 7 &CALL :showval %val% val
CALL :setra val 8 11 6 7&CALL :showval %val% val
CALL :setra val 2 4 6 7&CALL :showval %val% val
CALL :setra val 3 8 "" 6&CALL :showval %val% val
CALL :setra val 8 11 "" 6&CALL :showval %val% val
CALL :setra val 2 4 "" 6&CALL :showval %val% val
ECHO ==== add some extras =====
SET val=20&CALL :disp val 1 8 "" "" "The strange die rolls "
SET val=-4&CALL :disp val 0 8 "" "" "" "ghouls flee in fear"
SET val=-4&CALL :disp val 0 8 "" "" "There are " "arrows in stock"
SET val=-4&CALL :dispgz val 0 8 "" "" "There are " "arrows in stock"
SET val=14&CALL :dispgz val 0 8 "" "" "There are " "arrows in stock"
GOTO :EOF
:: set a variable %1 to %3 if it is less than %2
:setlt
CALL SET $1=%%%1%%
IF %$1% lss %2 SET "%1=%~3"
IF NOT DEFINED %1 SET "%1=%~2"
goto :eof
:: set a variable %1 to %3 if it is greater than %2
:setgt
CALL SET $1=%%%1%%
IF %$1% gtr %2 SET "%1=%~3"
IF NOT DEFINED %1 SET "%1=%~2"
goto :eof
:: set a variable %1 to %4 if it is less than %2 or %5 if it is greater than %3
:setra
CALL ECHO if %%%1%% .lt. %2 SET to "%~4" IF %%%1%% .gt. %3 to "%~5"
CALL :setlt %1 %2 %~4
CALL :setgt %1 %3 %5
goto :eof
:showval
CALL ECHO value was %1 is now %%%2%%
SET %2=%1
GOTO :eof
:: Display with limits.
:disp
setlocal
CALL SET $2=%%%1%%
CALL :setra $2 %2 %3 "%~4" "%~5"
ECHO %~6%$2% %~7
endlocal
GOTO :eof
:: Display with limits - but only if resolved value is greater than zero
:dispgz
setlocal
CALL SET $2=%%%1%%
CALL :setra $2 %2 %3 "%~4" "%~5"
IF %$2% gtr 0 ECHO %~6%$2% %~7
endlocal
GOTO :eof
Here's the output:
==== :setlt =====
value was 5 is now 5
value was 5 is now 6
value was 5 is now 5
value was 5 is now 5
value was 5 is now 1
value was 5 is now 5
==== :setgt =====
value was 5 is now 3
value was 5 is now 5
value was 5 is now 5
value was 5 is now 27
value was 5 is now 5
value was 5 is now 5
==== :setra =====
if 5 .lt. 3 SET to "" IF 5 .gt. 8 to ""
value was 5 is now 5
if 5 .lt. 8 SET to "" IF 5 .gt. 11 to ""
value was 5 is now 8
if 5 .lt. 2 SET to "" IF 5 .gt. 4 to ""
value was 5 is now 4
if 5 .lt. 3 SET to "6" IF 5 .gt. 8 to ""
value was 5 is now 5
if 5 .lt. 8 SET to "6" IF 5 .gt. 11 to ""
value was 5 is now 6
if 5 .lt. 2 SET to "6" IF 5 .gt. 4 to ""
value was 5 is now 4
if 5 .lt. 3 SET to "6" IF 5 .gt. 8 to "7"
value was 5 is now 5
if 5 .lt. 8 SET to "6" IF 5 .gt. 11 to "7"
value was 5 is now 6
if 5 .lt. 2 SET to "6" IF 5 .gt. 4 to "7"
value was 5 is now 7
if 5 .lt. 3 SET to "" IF 5 .gt. 8 to "6"
value was 5 is now 5
if 5 .lt. 8 SET to "" IF 5 .gt. 11 to "6"
value was 5 is now 8
if 5 .lt. 2 SET to "" IF 5 .gt. 4 to "6"
value was 5 is now 6
==== add some extras =====
if 20 .lt. 1 SET to "" IF 20 .gt. 8 to ""
The strange die rolls 8
if -4 .lt. 0 SET to "" IF -4 .gt. 8 to ""
0 ghouls flee in fear
if -4 .lt. 0 SET to "" IF -4 .gt. 8 to ""
There are 0 arrows in stock
if -4 .lt. 0 SET to "" IF -4 .gt. 8 to ""
if 14 .lt. 0 SET to "" IF 14 .gt. 8 to ""
There are 8 arrows in stock
And now I'm free to waffle a bit...
After setting val to 5, there are many lines of the basic format
CALL :setlt val 3&CALL :showval %val% val
The routine :showval shows the current value of val and then resets it to its original value. In that way, I could report the result of the preceding CALL and reset the value to whatever value I chose (but I didn't use that feature...)
The parameters of the :setlt calls are variable, limit, forced_value - where forced_value is optional. If the forced value is not specified, the limit will be used.
So :setlt with parameters of val 3 will set the value of val to 3 if its current value is less than 3 - but if the parameters were val 6 1 then if the current value of val is less than 6, its value will be changed to 1.
So the :showval routine shows the result in each case, then resets val to 5.
:setgt is similar, just setting the value if the current value is greater than rather than less than.
Next group is the :setra which has parameters var minval maxval forceifltmin forceifgtmax - the only kink being that if forceifltmin is not used but forceiflmax is used, then forceifltmin must be an empty parameter ("").
I've added the call echo... line at the start of :setra purely to show what's happening - it's useful for debugging. Just REM or :: that line so you can turn debugging on or off.
(Tip: with debug-lines, you could try
set "debug=REM "
%debug%echo this is a debug line
Simply set debug to either REM or nothing to turn your debugging lines off or on)
Last is the :disp and :dispgz routines. These are very slightly different. They deliberately don't change the value of the variable and are designed to display the value as if it was in the range, There are an additional two parameters - both optional being the text-before and text-after value. Both should be supplied "quoted".
This time, there's simply a display of text-beforevalue text-after so you can build messages as shown.
If you don't want to display a line containing a value unless the value after applying the range-checks is >0 then use :dispgz