For Loop on Windows Batch

Question

I am doing some batch practice and I am trying to do a loop to go backwards and count the numbers from 110 to 100, but only the even numbers. I almost got it to work, but for so

Answer 1

There are several correct ways to do this and one wrong way. The bad way is this:

for /l %%x in (110, -2, 100) do (
   set /a totalCount = %totalCount% + %%x
)

Because %totalCount% is expanded just once, before the for is executed, so the value of the sum is always 0 plus each term.

One possible solution is use Delayed Expansion as Dale suggested:

echo off
setlocal enabledelayedexpansion

set /a totalCount = 0

for /l %%x in (110, -2, 100) do (
   set /a totalCount = !totalCount! + %%x
)

echo total is %totalCount%

This way, the value of !totalCount! is correctly replaced in each for cycle. However, this is not needed either, because set /A command takes the current value of the variables by itself each time it is executed:

echo off

set /a totalCount = 0

for /l %%x in (110, -2, 100) do (
   set /a totalCount = totalCount + %%x
)

echo total is %totalCount%

Moreover, set /A command have a way to increment a variable that don't even requires to write its name, so the matter of this discussion completely dissapear:

echo off

set /a totalCount = 0

for /l %%x in (110, -2, 100) do (
   set /a totalCount += %%x
)

echo total is %totalCount%

Answer 2

Try changing %totalCount% to !totalCount!. Therefore, the code should look like this:

echo off
setlocal enabledelayedexpansion

set /a totalCount = 0

for /l %%x in (110, -2, 100) do (
   set /a totalCount = !totalCount! + %%x
)

echo total is !totalCount!