批量 - 变量在ECHO和IF提供不同的输出

Question

I am currently implementing a postprocess in batch, and after some changes a few code snipplets simply don't work anymore....

What I am trying to do:

@echo off & setlocal
ECHO %netUse%                        //For debugging!
IF NOT "%netUse%" == "" (            //Double checking if Variable is set
    IF %netUse% EQU 1 (
        IF %netUsePW% EQU 1 (
            NET USE %netUseLetter% %netPath% %pw% /user:%netUser% 
        )
        IF %netUsePW% EQU 0 (
            NET USE %netUseLetter% %netPath%
        )
    )
)

When I run that code, this is the output:

C:\Program Files (x86)\ID GmbH\PRODETTE\DAX\ISDN>ECHO 0
0   <--- That's right! It is set to ZERO via a "configuration" Batch
"1" kann syntaktisch an dieser Stelle nicht verarbeitet werden.   <-- ???

C:\Program Files (x86)\ID GmbH\PRODETTE\DAX\ISDN>               IF  EQU 1 (  <-- Why isn't it comparing the variable?

And just for completionists sake, I am loading all of these variables form another batch file, "Settings.bat" I am running that file via CALL :postCopySettings.bat

contents:

SET netUse=0
SET netUsePW=
SET netUseLetter=
SET netPath=
SET netUser=
SET pw=
SET configLoaded=1

(Since netUse is 0, I don't need to populate the other variables... right?)

TL:DR: Batch doesn't work, but I don't know why.

Answer 1

IF NOT "%netUse%" == "" (            //Double checking if Variable is set
    IF %netUse% EQU 1 (
        IF %netUsePW% EQU 1 (

No point in testing "netuse" then complaining that "netusePW" is not set.

Answer 2

The problem is that variable netUsePW is not set.

When netUse is set to 0 , and netUsePW , netUseLetter , netUsePath , pw are all empty, your code...:

@echo off & setlocal
ECHO %netUse%
IF NOT "%netUse%" == "" (
    IF %netUse% EQU 1 (
        IF %netUsePW% EQU 1 (
            NET USE %netUseLetter% %netPath% %pw% /user:%netUser%
        )
        IF %netUsePW% EQU 0 (
            NET USE %netUseLetter% %netPath%
        )
    )
)

...expands to...:

@echo off & setlocal
ECHO 0
IF NOT "0" == "" (
    IF 0 EQU 1 (
        IF  EQU 1 (
            NET USE    /user:0
        )
        IF  EQU 0 (
            NET USE  
        )
    )
)

As you can see, there are two syntax issues, which cause the error:

 IF EQU 1 IF EQU 0 

Although netUse is set to 0 and you therefore expect the statements after IF %netUse% EQU 1 not to be executed, they are still parsed, because the entire code block is parsed before any commands are executed.

---

To overcome this, there are several ways:

1. Preset variables with non-empty values:

    @echo off & setlocal ECHO %netUse% IF "%netUse%" == "" (set "netUse=-1" & set "setUsePW=-1") IF NOT "%netUse%" == "" ( IF %netUse% EQU 1 ( IF %netUsePW% EQU 1 ( NET USE %netUseLetter% %netPath% %pw% /user:%netUser% ) IF %netUsePW% EQU 0 ( NET USE %netUseLetter% %netPath% ) ) ) 

2. Avoid code blocks by changing the logic a bit and using goto :

    @echo off & setlocal ECHO %netUse% IF "%netUse%" == "" goto :SKIP IF %netUse% NEQ 1 goto :SKIP IF %netUsePW% EQU 1 ( NET USE %netUseLetter% %netPath% %pw% /user:%netUser% ) IF %netUsePW% EQU 0 ( NET USE %netUseLetter% %netPath% ) :SKIP 

3. Avoid code blocks by moving some code into subroutines and using call to call them:

    @echo off & setlocal ECHO %netUse% IF NOT "%netUse%" == "" call :TEST "%netUse%" "%netUsePW%" "%netUseLetter%" "%netPath%" "%pw%" exit /B :TEST IF %~1 EQU 1 call :TESTPW "%~1" "%~2" "%~3" "%~4" "%~5" exit /B :TESTPW IF %~2 EQU 1 ( NET USE %~3 %~4 %~5 /user:%~1 ) IF %~2 EQU 0 ( NET USE %~3 %~4 ) exit /B 

4. Enable and apply delayed expansion to do the variable expansion during execution rather than while parsing:

    @echo off & setlocal EnableDelayedExpansion ECHO %netUse% IF NOT "%netUse%" == "" ( IF !netUse! EQU 1 ( IF !netUsePW! EQU 1 ( NET USE %netUseLetter% %netPath% %pw% /user:!netUser! ) IF !netUsePW! EQU 0 ( NET USE %netUseLetter% %netPath% ) ) )