Replace n-th element in CSV string - windows

Question

I try to replace the n-th element of a CSV string, without knowing his value. For example, here is my string :
*;*;*;element_to_replace;*;*
With * an undefined string, it can be anything.
So i tried to use :
for /F "delims=" %%w in (file\workstation) do (
set line=%%w
if !compt! NEQ 0 (
set new_line=!line:*;*;*;*=*;*;*;new_value!
#echo !new_line! >> file\tmp_workstation
) else (
#echo !header_workstation! >> file\tmp_workstation
)
set /A "compt+=1"
)
It doesn't work. Am i doing something wrong ?

Answer 1

#echo off
setlocal enabledelayedexpansion
REM you want to replace token 4:
for /f "tokens=1-4,* delims=;" %%a in (t.csv) do (
echo %%a;%%b;%%c;replaced;%%e
)
tokens=1-4,* means: take the first four tokens, the fifth token is "the rest of the line". %%a is the first token, %%b is the second one etc.
You want to write token1;token2;token3,"replacement string for the fourth token(%%d)";"rest of the line" (fifth token).

Answer 2

Supposing the * characters do not appear literally within your data and it does also not contain any ? marks, you could use the following code snippet:
#echo off
setlocal EnableExtensions DisableDelayedExpansion
rem // Define constants here:
set "INFILE=file\workstation"
set "OUTFILE=file\tmp_workstation"
set "SEPARATOR=;"
set /A "COL_NUM=4"
set "COL_NEWVAL=new_value"
rem // A single redirection:
> "%OUTFILE%" (
set "HEADER=#"
rem // Read CSV file line by line:
for /F usebackq^ delims^=^ eol^= %%L in ("%INFILE%") do (
set "LINE=%%L"
if defined HEADER (
rem // Skip header from replacement:
set "NEW_LINE=%%L"
set "HEADER="
) else (
set "NEW_LINE=" & set "SEP=" & set /A "IDX=0"
rem // Toggle delayed expansion to not lose any `!`:
setlocal EnableDelayedExpansion
set "LINE=!LINE:"=""!^"
rem // Use standard `for` loop to enumerate column values:
for %%I in ("!LINE:%SEPARATOR%=","!") do (
endlocal
set /A "IDX+=1"
set "ITEM=%%~I"
setlocal EnableDelayedExpansion
rem // Replace column value if index matches:
if !IDX! EQU %COL_NUM% (
endlocal
set "ITEM=%COL_NEWVAL%"
setlocal EnableDelayedExpansion
) else (
if defined ITEM set "ITEM=!ITEM:""="!^"
)
rem /* Collect line string;
rem `for /F` loop to pass string beyond `endlocal` barrier: */
for /F delims^=^ eol^= %%E in ("!NEW_LINE!!SEP!!ITEM!") do (
endlocal
set "NEW_LINE=%%E"
setlocal EnableDelayedExpansion
)
endlocal
set "SEP=%SEPARATOR%"
setlocal EnableDelayedExpansion
)
endlocal
)
rem // Output newly built line:
setlocal EnableDelayedExpansion
echo(!NEW_LINE!
endlocal
)
)
endlocal
exit /B