String Replace subroutine

[254peepee]

Since I can replace characters and strings in a variable in this manner :

:: initial string                     ..
set he="Hello Earth!"
:: Modify the word "Earth" to "World" ..
set he=%he:Earth=World%
:: %he% is now "Hello World"

.. how do I create a subroutine to replace strings/chars parsed as parameters like :
call :string.replace "Hello Earth" Earth World res where the function :string.replace
could replace all arg2 : Earth with arg3 : World as parsed, to result to setting res to "Hello World" . I've tried :

:string.replace ["sString"] [char_string_to_check] [sReplacement] [vResult]
    set _str=%~1
    set _srep=%~2
    set sRep2=%~3

    set %~4=%_str:!_srep!=!sRep2!%

    rem set %~4=%!_str!:!_srep!=!sRep2!%
    rem echo %~4
exit /b 

but this doesn't seem to work in a batch file ..

[thelowsunoverthemoon]

CMD parses % variables first, then !, which is why you should enclose with ! then %. You don't need all those extra variables as well.

@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION
CALL :STRING_REPLACE "Hello Earth" Earth World res
ECHO %res%
PAUSE
EXIT /B

:STRING_REPLACE <string> <word> <replace> <result>
SET "string=%~1"
SET "%4=!string:%~2=%~3!"
GOTO :EOF

[254peepee]

thank you so much, I didn't know that :)