批处理文件:SET变量=字符串不起作用 [英] Batch file : SET variable=string doesn't work

问题描述

我有此代码:

if %Ret:~6,4% EQU %Year% (
SET test=text
ECHO %test%
) else (
ECHO NO
)

代码进入if循环，但始终返回Echo关闭！ 我注意=前后的空格. 有什么想法吗?

The code enters in the if loop but it returns always Echo is off! I've pay attention to the space before and after the =. Any ideas?

推荐答案

今年此类问题的编号#342.

Number #342 of this type of question this year.

在执行任何行之前，解析一个块时，扩展百分比就会增加.
因此，echo %test%会在设置变量之前展开.

Percent expansion occours when a block is parsed, before any line is executed.
So the echo %test% is expanded before the variable is set.

因此存在延迟扩展，该延迟扩展在执行一行时扩展.

Therefor exists the delayed expansion, which expands when a line is executed.

setlocal EnableDelayedExpansion
if "%Ret:~6,4%" EQU "%Year%" (
  SET test=text
  ECHO !test!
) else (
  ECHO NO
)

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