使用!而不是“空字符串检查”

@echo off
SET a=
SET b=Hello
IF !%a%! == !! echo String a is empty
IF !%b%! == !! echo String b is empty

我根据这里的答案创建了这个小批处理脚本，因为有很多有效的答案。只要遵循相同的格式，可以随意添加:

REM Parameter-testing

Setlocal EnableDelayedExpansion EnableExtensions

IF NOT "%~1"=="" (echo Percent Tilde 1 failed with quotes) ELSE (echo SUCCESS)
IF NOT [%~1]==[] (echo Percent Tilde 1 failed with brackets) ELSE (echo SUCCESS)
IF NOT  "%1"=="" (echo Quotes one failed) ELSE (echo SUCCESS)
IF NOT [%1]==[] (echo Brackets one failed) ELSE (echo SUCCESS)
IF NOT "%1."=="." (echo Appended dot quotes one failed) ELSE (echo SUCCESS)
IF NOT [%1.]==[.] (echo Appended dot brackets one failed) ELSE (echo SUCCESS)

pause

我在不到一个月的时间里就被录取了(尽管这是8年前的要求)……我希望他/她现在已经超越批处理文件了。: -) 我以前经常这么做。但我不确定最终目标是什么。如果他/她像我一样懒，我的go.bat就能解决这些问题。(见下文) 但是，1，如果您直接将输入作为命令使用，则OP中的命令可能无效。也就是说,

"C:/Users/Me"

是无效命令(如果您在不同的驱动器上，则过去是无效命令)。你得把它分成两部分。

C:
cd /Users/Me

第二，'defined'和'undefined'是什么意思?GIGO。我使用默认值来捕捉错误。如果输入没有被捕获，它将被删除以帮助(或默认命令)。所以，没有输入不是错误。您可以尝试cd到输入并捕捉错误(如果有的话)。(好的，使用go "downloads(只有一个括号)被DOS捕获。(严厉的!)

cd "%1"
if %errorlevel% neq 0 goto :error

并且，3，引号只需要围绕路径，而不是命令。也就是说,

"cd C:\Users" 

是不好的(或者在过去习惯了)，除非你在不同的驱动器上。

cd "\Users" 

是功能。

cd "\Users\Dr Whos infinite storage space"

如果你的路径上有空格，就有用。

@REM go.bat
@REM The @ sigh prevents echo on the current command
@REM The echo on/off turns on/off the echo command. Turn on for debugging
@REM You can't see this.
@echo off
if "help" == "%1" goto :help

if "c" == "%1" C:
if "c" == "%1" goto :done

if "d" == "%1" D:
if "d" == "%1" goto :done

if "home"=="%1" %homedrive%
if "home"=="%1" cd %homepath%
if "home"=="%1" if %errorlevel% neq 0 goto :error
if "home"=="%1" goto :done

if "docs" == "%1" goto :docs

@REM goto :help
echo Default command
cd %1
if %errorlevel% neq 0 goto :error
goto :done

:help
echo "Type go and a code for a location/directory
echo For example
echo go D
echo will change disks (D:)
echo go home
echo will change directories to the users home directory (%homepath%)
echo go pictures
echo will change directories to %homepath%\pictures
echo Notes
echo @ sigh prevents echo on the current command
echo The echo on/off turns on/off the echo command. Turn on for debugging
echo Paths (only) with folder names with spaces need to be inclosed in         quotes (not the ommand)
goto :done

:docs
echo executing "%homedrive%%homepath%\Documents"
%homedrive%
cd "%homepath%\Documents"\test error\
if %errorlevel% neq 0 goto :error
goto :done

:error
echo Error: Input (%1 %2 %3 %4 %5 %6 %7 %8 %9) or command is invalid
echo go help for help
goto :done

:done

脚本1:

输入(“删除引号。”cmd"这是一个测试")

@ECHO OFF

REM Set "string" variable to "first" command line parameter
SET STRING=%1

REM Remove Quotes [Only Remove Quotes if NOT Null]
IF DEFINED STRING SET STRING=%STRING:"=%

REM IF %1 [or String] is NULL GOTO MyLabel
IF NOT DEFINED STRING GOTO MyLabel


REM   OR   IF "." equals "." GOTO MyLabel
IF "%STRING%." == "." GOTO MyLabel

REM GOTO End of File
GOTO :EOF

:MyLabel
ECHO Welcome!

PAUSE

输出(没有，%1不是空的，空的，或NULL):

使用上面的脚本运行("Remove Quotes.cmd")，不带任何参数

输出(%1为空白、空或NULL):

Welcome!

Press any key to continue . . .

注意:如果你在If () ELSE()语句中设置了一个变量，它将在退出If语句后才对DEFINED可用(除非“延迟变量扩展”被启用;一旦启用，请使用感叹号“!”来代替百分比“%”符号}。

例如:

脚本2:

输入(“删除引号。”cmd"这是一个测试")

@ECHO OFF

SETLOCAL EnableDelayedExpansion

SET STRING=%0
IF 1==1 (
  SET STRING=%1
  ECHO String in IF Statement='%STRING%'
  ECHO String in IF Statement [delayed expansion]='!STRING!'
) 

ECHO String out of IF Statement='%STRING%'

REM Remove Quotes [Only Remove Quotes if NOT Null]
IF DEFINED STRING SET STRING=%STRING:"=%

ECHO String without Quotes=%STRING% 

REM IF %1 is NULL GOTO MyLabel
IF NOT DEFINED STRING GOTO MyLabel

REM GOTO End of File
GOTO :EOF

:MyLabel
ECHO Welcome!

ENDLOCAL
PAUSE

输出:

C:\Users\Test>"C:\Users\Test\Documents\Batch Files\Remove Quotes.cmd" "This is a Test"  
String in IF Statement='"C:\Users\Test\Documents\Batch Files\Remove Quotes.cmd"'  
String in IF Statement [delayed expansion]='"This is a Test"'  
String out of IF Statement='"This is a Test"'  
String without Quotes=This is a Test  

C:\Users\Test>  

注意:它还会从字符串中删除引号。

例如(使用脚本1或2): c:\ users \ test \ documents \批处理文件>"删除引号。cmd"这是"一个"测试"

输出(脚本2):

String in IF Statement='"C:\Users\Test\Documents\Batch Files\Remove Quotes.cmd"'  
String in IF Statement [delayed expansion]='"This is "a" Test"'  
String out of IF Statement='"This is "a" Test"'  
String without Quotes=This is a Test  

在脚本2中不带任何参数地执行("Remove Quotes.cmd"):

输出:

Welcome!

Press any key to continue . . .

使用!而不是“空字符串检查”

@echo off
SET a=
SET b=Hello
IF !%a%! == !! echo String a is empty
IF !%b%! == !! echo String b is empty

我测试下面的代码，它是好的。

@echo off

set varEmpty=
if not "%varEmpty%"=="" (
    echo varEmpty is not empty
) else (
    echo varEmpty is empty
)
set varNotEmpty=hasValue
if not "%varNotEmpty%"=="" (
    echo varNotEmpty is not empty
) else (
    echo varNotEmpty is empty
)