set "%~1=DosTips"
goto:eof
Script Output: Script Output
var1 after : DosTips
Example - Returning Values using Variable Reference - An Example showing how it works
Description: This code shows how the var1 variable is being passed into a :myGetFunc function simply by passing the variable name. Within the :myGetFunc function the command processor works like this:
1.Reads the set command into memory: set "%~1=DosTips"
2.Expand the variables, i.e. %~1 like this: set "var1=DosTips"
3.Finally execute the command and assign the new string to var1
Script:
@echo off
set "var1=CmdTips"
echo.var1 before: %var1%
call:myGetFunc var1
echo.var1 after : %var1%
echo.&pause&goto:eof
::--------------------------------------------------------
::-- Function section starts below here
::--------------------------------------------------------
:myGetFunc - passing a variable by reference
set "%~1=DosTips"
goto:eof
Script Output: Script Output
var1 before: CmdTips
var1 after : DosTips
Press any key to continue . . .
Local Variables in Functions - How to avoid name conflicts and keep variable changes local to the function
Description: The SETLOCAL causes the command processor to backup all environment variables. The variables can be restored by calling ENDLOCAL. Changes made im between are local to the current batch. ENDLOCAL is automatically being called when the end of the batch file is reached, i.e. by calling GOTO:EOF.
Localizing variables with SETLOCAL allows using variable names within a function freely without worrying about name conflicts with variables used outside the function.
Script:
@echo off
set "aStr=Expect no changed, even if used in function"
set "var1=No change for this one. Now what?"
echo.aStr before: %aStr%
echo.var1 before: %var1%
call:myGetFunc var1
echo.aStr after : %aStr%
echo.var1 after : %var1%
echo.&pause&goto:eof
::--------------------------------------------------------
::-- Function section starts below here
::--------------------------------------------------------
:myGetFunc - passing a variable by reference
SETLOCAL
set "aStr=DosTips"
set "%~1=%aStr%"
ENDLOCAL
goto:eof
Script Output: Script Output
aStr before: Expect no changed, even if used in function
var1 before: No change for this one. Now what?
aStr after : Expect no changed, even if used in function
var1 after : No change for this one. Now what?
Press any key to continue . . .
Returning Local Variables - How to pass return values over the ENDLOCAL barrier
