在 for 循环中初始化的批处理文件变量 [英] Batch file variables initialized in a for loop

问题描述

我有一个批处理文件，它通过 for 循环内的 SET 为磁盘上的一组文件初始化变量:

I have a batch file which initializes variables via SET inside a for loop, for a set of files on disk:

for %%f in (%MYTARGETDIR%*config.xml) do (
  SET TMPFILE=%%F.tmp

  echo In loop %TMPFILE%
)

echo End loop %TMPFILE%

当我在全新的命令 shell(未定义 TMPFILE)中运行它时，循环内回显为空，但结束循环回显不是.

when I run this in a brand new command shell (without TMPFILE defined) the In loop echo is empty, but the end loop echo is not.

当我第二次运行时，它已经设置，并输出它的值，忽略设置直到循环关闭.

When I run a second time, its already set, and outputs its value, ignoring the set until the loop closes.

为什么会这样，以及解决方法是什么?

Ideas why this is, and what the workaround is?

推荐答案

那是因为 ( ) 块只被解析一次，它在运行循环之前替换了 %TMPFILE%.

That's because the ( ) block is parsed only once, it substitutes %TMPFILE% before it runs your loop.

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