How to use Windows batch for bicirculation - windows

Question

two files 1.txt 2.txt
1.txt
a2441
b4321
p8763
2.txt
Apple
banana
peach
I want to generated content in 12.bat
ren a2441 Apple
ren b4321 banana
ren p8763 peach
I try to write like this but failed
#echo on
for /f %%a in (1.txt) do (
for /f %%b in (2.txt ) do (
ren %%a %%b>>12.bat
)
)
pause
How can I achieve my desired results? help me,thks

Answer 1

It is not so straightforward. You'll need to skip increasing amount of lines in the inner loop , but because of the FOR parsing you'll need additional subroutine call.And if there are empty lined they need to be stripped with findstr for more accurate skipping of the lines. Also skip argument in FOR does not accept 0 so also an if is needed.
#echo off
setlocal ENABLEDELAYEDEXPANSION
set /a s=0
for /f "tokens=* delims=" %%a in (1.txt) do (
call :inner !s!
echo ren %%a !second!
set /a s=s+1
)
endlocal
pause
exit /b
:inner
set "second="
if %1==0 (
for /f "tokens=* delims=" %%b in ('findstr /r "[a-zA-Z]" "2.txt"') do (
if not defined second set "second=%%b"
)
) else (
for /f "skip=%1 tokens=* delims=" %%b in ('findstr /r "[a-zA-Z]" "2.txt"' ) do (
if not defined second set "second=%%b"
)
)

Answer 2

The problem with anidated loops is that for each line of the outer file/loop all the lines of the inner file/loop are processed.
One simple solution is to number the lines of both files and only generate the output line when both numbers match. Quick and dirty:
#echo off
setlocal enableextensions disabledelayedexpansion
>"12.bat" (
for /f "tokens=1,* delims=:" %%a in ('findstr /n "^" 1.txt') do (
for /f "tokens=1,* delims=:" %%c in ('findstr /n "^" 2.txt') do (
if %%a==%%c (
echo ren %%b %%d
)
))
)
This code just uses findstr to generate line numbers (/n) for each of the input files, and using the delims and tokens clauses of the for /f command to separate them from the original line contents (note: if the lines could start with a colon, more code is needed). If the line number in first file matches the line number in second file the command is echoed (there is a active output redirection to the final file)
Another option is to assign each file to a input stream and to read them using set /p operations from each of the streams
#echo off
setlocal enableextensions disabledelayedexpansion
call :processFiles 9<"1.txt" 8<"2.txt" >"12.bat"
goto :eof
:processFiles
<&9 set /p f1= || goto :eof
<&8 set /p f2= || goto :eof
echo ren %f1% %f2%
goto :processFiles
In the call to the subroutine we assign each file to a stream. Inside the subroutine each stream is read with set /p (note: set /p can not read lines longer than 1021 characters)