REM START
for /f "delims=" %%j in ('type a.txt') do (
set /a i=%%j
echo %i%
if "%i%" == "1" (
echo txt=1
)
if "%i%" == "2" (
echo txt=2
)
if "%i%" == "3" (
echo txt=3
)
)
REM END
@echo off
setlocal enabledelayedexpansion
for /f "delims=" %%a in ('type a.txt') do (
set "i=%%a"
echo.!i!
for /l %%b in (1 1 3) do (if "!i!"=="%%b" echo txt^=%%b)
)
echo.&pause