windows 批量延迟扩展不起作用
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Batch delayed expansion not working
提问by Richard
Ok, I'm getting crazy and I don't know what else to do, I've tried several things and nothing is working.
好吧，我快疯了，我不知道还能做什么，我已经尝试了几件事，但没有任何效果。
Look at this sample code (test.cmd):
看看这个示例代码（test.cmd）：
setlocal enabledelayedexpansion enableextensions
set VAR=before
if "%VAR%" == "before" (
set VAR=after;
if "%VAR%" == "after" @echo If you see this, it worked
)
This is the generated output:
这是生成的输出：
D:\>ver
Microsoft Windows [Version 6.1.7600]
D:\>test.cmd
D:\>setlocal enabledelayedexpansion enableextensions
D:\>set VAR=before
D:\>if "before" == "before" (
set VAR=after;
if "before" == "after"
)
D:\>
Am I doing something wrong?
难道我做错了什么？
This is just a test, the code I need uses variables too and needs delayed expansion, but it this simple test doesn't work the other wont work either (I've tried, I ended up with a simple example to test if it worked).
这只是一个测试，我需要的代码也使用变量并且需要延迟扩展，但是这个简单的测试不起作用，另一个也不起作用（我已经尝试过，我最终得到了一个简单的例子来测试它是否有效）。
EDIT: New code and output:
编辑：新代码和输出：
test.cmd:
测试.cmd：
@echo off
setlocal enabledelayedexpansion enableextensions
set VAR=before
if "%VAR%" == "before" (
set VAR=after;
if "!VAR!" == "after" (
echo It worked.
) else (
echo It didn't work.
)
)
Output:
输出：
D:\>test.cmd
It didn't work.
D:\>
回答by atzz
You have to use !var!for delayed expansion. %var%is always expanded on parse stage.
您必须使用!var!延迟扩展。%var%总是在解析阶段扩展。
I.e., change your code to
即，将您的代码更改为
setlocal enabledelayedexpansion enableextensions
set VAR=before
if "%VAR%" == "before" (
set VAR=after
if "!VAR!" == "after" @echo If you see this, it worked
)
回答by user3200692
At the beginning of the cmd prompt, you must type “CMD /V” OR “CMD /V:ON”
在cmd提示符的开头，你必须输入“CMD /V”或“CMD /V:ON”
After this testing code should work
在此测试代码应该工作之后
SETLOCAL EnableDelayedExpansion
Set "_var=first"
Set "_var=second" & Echo %_var% !_var!
You should be able to see output “first second”
您应该能够看到“第一秒”的输出
回答by rapster
dont use == , in batch you must use EQU
不要使用 == ，批量你必须使用 EQU
For Example write:
例如写：
if %bla% EQU %blub% echo same
回答by Jason Li
I found your problem.
我发现了你的问题。
set VAR=after;
delete ;from the code above
;从上面的代码中删除
