identify or delete equal sign (=) in Windows command script environment variable

Question

Is there methods to do the subject? For example, we can't simply replace equal sign usual way through substring replacing syntax %variable:substring1=substring2%, because substring1 can't contain equal sign.

Answer 1

What about a simple loop that walks through the string and checks every character against =?

@echo off
setlocal EnableExtensions DisableDelayedExpansion

rem // Define constants here:
set "STRING=%~1" & rem // (string from first command line argument)
set "SEARCH==" & rem // (specify a single character here)
set "REPLAC=" & rem // (specify an arbitrary string here)

rem // Check search string for validity (one character):
if not defined SEARCH ((>&2 echo ERROR: no search string defined!) & exit /B 1)
setlocal EnableDelayedExpansion
if not "!SEARCH:~1!"=="" ((>&2 echo ERROR: search string too long^^!) & exit /B 1)
rem // Loop through each character of the string:
set "RESULT="
:LOOP
if not defined STRING goto :QUIT
rem // Compare current character with search string:
set "CHAR=!STRING:~,1!"
if "!CHAR!"=="!SEARCH!" (
    rem // Match found, so replace character:
    set "RESULT=!RESULT!!REPLAC!"
) else (
    rem // No match found, so keep character:
    set "RESULT=!RESULT!!CHAR!"
)
rem // Remove processed character from (remaining) string:
set "STRING=!STRING:~1!"
goto :LOOP
:QUIT
rem // Return result here finally:
echo(!RESULT!
endlocal

endlocal
exit /B

---

This should be a bit better in terms of performance, because there are less string manipulations:

@echo off
setlocal EnableExtensions DisableDelayedExpansion

rem // Define constants here:
set "STRING=%~1" & rem // (string from first command line argument)
set "SEARCH==" & rem // (specify a single character here)
set "REPLAC=" & rem // (specify an arbitrary string here)

rem // Check search string for validity (one character):
if not defined SEARCH ((>&2 echo ERROR: no search string defined!) & exit /B 1)
setlocal EnableDelayedExpansion
if not "!SEARCH:~1!"=="" ((>&2 echo ERROR: search string too long^^!) & exit /B 1)
rem // Loop through each character of the string:
set /A "INDEX=0" & set "RESULT="
if not defined STRING goto :QUIT
:LOOP
rem // Compare currently indexed character with search string:
set "CHAR=!STRING:~%INDEX%,1!"
if not defined CHAR goto :QUIT
if "!CHAR!"=="!SEARCH!" (
    rem // Match found, so replace character:
    set "RESULT=!RESULT!!REPLAC!"
) else (
    rem // No match found, so keep character:
    set "RESULT=!RESULT!!CHAR!"
)
rem // Increment character index:
set /A "INDEX+=1"
goto :LOOP
:QUIT
rem // Return result here finally:
echo(!RESULT!
endlocal

endlocal
exit /B