Windows 批处理变量不会设置 [英] Windows Batch Variables Won't Set

问题描述

我想我在 Window 的批处理脚本中遇到了一个错误.

I think I ran into a bug in Window's batch scripting.

我无法设置扩展 if 语句中的变量.

I cannot set variables that are in an expanded if statement.

这是我的脚本的一个孤立部分:

Here is an isolated part of my script:

@echo off

set success=1
set Version=12345
set Target=Client
set Type=456
set dir=
set zip=

if "%Version%"=="" set success=0
if "%Type%"=="" set success=0

if 1==1 set test=42

if %success%==1 (
    set test2=57005
    if "%Target%"=="Client" (
        set dir=ModName v%Version%
        set zip=ModName v%Version% %Type%.zip
        echo Version: %Version%
        echo    Type: %Type%
        echo.
        echo  Target: %Target%
        echo     dir: %dir%
        echo     zip: %zip%
        echo.
        echo    test: %test%
        echo   test2: %test2%
    )
) else (
    echo Not successful.
)

这是一个全新的 cmd 实例的输出:

This is the output from a brand new instance of cmd:

C:UsersRandomClownDesktop>test.bat
Version: 12345
   Type: 456

 Target: Client
    dir:
    zip:

   test: 42
  test2:

您应该注意的是单行 if 语句正确设置了内容.多行 if 将执行任何非集合的操作.我不认为我错过了什么.此外，多行 if 语句正确执行了正确的行，因为 else ( echo Not success. ) 行没有执行.

What you should notice is that the single line if statement correctly sets stuff. The multiline if will perform anything that is NOT a set. I dont think I missed anything. Also, the multiline if statement is correctly executing the right lines, as the else ( echo Not successful. ) lines did not execute.

为什么这些行没有执行?

Why did the lines not execute?

推荐答案

你错过了一些东西 ;-)

You missed something ;-)

cmd 在命令被解析时扩展变量，而不是在它们运行时.碰巧带有块 ( ... )(或实际上任何块)的 if 或 for 语句在那种情况.因此，当您在块中设置变量并尝试在同一个块中使用它们时，不再有变量 - 它们被替换为变量在块执行之前之前的值.

cmd expands variables when commands are parsed, not when they are run. It so happens that an if or for statement with a block ( ... ) (or actually any block) counts as a single command in that case. So when you set variables inside a block and try using them in the same block there are no variables anymore – they were replaced by the values the variables had before the block even executed.

贴一个

setlocal enabledelayedexpansion

在批处理文件的开头并使用 !zip! 而不是 %zip%.有关问题的详细讨论，请参阅 help set.

at the start of your batch file and use !zip! instead of %zip%. See help set for a detailed discussion of the problem.

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