How to generate reports for every 100 files using Batch Scipt

Here's the scenario, for example I have list of files listed in pairing.txt. Now I am doing comparison for all the files listed then generating reports. Now, I want to have a feature that will enable the user how many files he want for one report. For example, I have 205 files listed.

FIRST 100 -    Report1.html
NEXT 100 -     Report2.html
Remaining 5 -  Report3.html

Here my actual code

for /f "tokens=2-4" %%a in ('type c:\user\pairing.txt') do (
  set /A Counter+=1
  echo Processing  ColumnA : %%a  ColumnB: %%b 
  echo  Processing  ColumnA : %%a  ColumnB: %%b >>comparison.log
  %varBCpath% %varBCscript% c:\user\ColumnA\%%a c:\user\ColumnB\%%b "c:\comp\report.html" "%title%" /silent
  type  c:\user\report.html >> c:\user\report\Report.html
)

What it does is, It will get the files listed in pairing.txt and compare it using beyond compare. Now by default, all comparison will be displayed in 1 html report. What if I want the user to have the option to enter how many files he want to display in every html report?

Solution

Supposing correctness of the code provided in question, an user input expected in set /P command and tested whether numeric and positive; output file numbering is done in the :myType subroutine as follows:

:: some code here

:againhowmany
set /A "howmany=100"
set /P "howmany=how many files do you want for one report (Enter=%howmany%) "
set /A "howmany%%=100000"
if %howmany% LEQ 0 goto :againhowmany 

set /A "Counter=0"
set /A "ReportNo=1"

for /f "tokens=2-4" %%a in ('type c:\user\pairing.txt') do (
  set /A "Counter+=1"
  echo Processing  ColumnA : %%a  ColumnB: %%b 
  echo  Processing  ColumnA : %%a  ColumnB: %%b >>comparison.log
  %varBCpath% %varBCscript% c:\user\ColumnA\%%a c:\user\ColumnB\%%b "c:\comp\report.html" "%title%" /silent
  call :myType
)

:: some code here 
goto :eof

:myType
  type  c:\user\report.html >> c:\user\report\Report%ReportNo%.html
  set /A "Counter%%=%howmany%"
  if %Counter% EQU 0 set /A "ReportNo+=1" 
goto :eof

Final output files should be

c:\user\report\Report1.html
c:\user\report\Report2.html
c:\user\report\Report3.html
...

Edit: according to OP's comment: For example I have 12 list of files, then I entered 10 files for each report. How about the remaining 2 files?

Under that clause final output files should be

Report1.html   - files (pair)  1..10
Report2.html   - files (pair) 11..12

Note the only script changes:

CountNo variable renamed to ReportNo for better insight;
ReportNo initiated to 1 (to observe instructions in question).

Edit 2: I had forgotten set /a command provides (32 bit signed) integer arithmetic, so the :myType procedure could be simplified as follows:

:myType
  set /A "ReportNo=(%Counter%-1)/%howmany%+1"
  type  c:\user\report.html >> c:\user\report\Report%ReportNo%.html
goto :eof