我该如何增加一个DOS变量在FOR / F循环？ [英] How do I increment a DOS variable in a FOR /F loop?

问题描述

我想从文件中读取文本行，并增加一个计数器，所以我可以最终在DOS模拟阵列。

I'm trying to read text lines from a file, and increment a counter so I can eventually simulate an array in DOS.

我希望能够文本行存放在DOS阵列进行进一步的处理。

I'd like to be able to store the lines of text in a DOS array for further processing.

我现在的尝试是：

set TEXT_T="myfile.txt"

set /a c=1

FOR /F "tokens=1 usebackq" %%i in (%TEXT_T%) do (
set /a c=c+1
echo %%i,  %c%
)

但变量c不递增;它停留在1。

But the variable c is not incrementing; it stays at 1.

建议表示欢迎。

谢谢，迈克

推荐答案

与code段的问题是变量被扩展的方式。当第一次宣读了一份声明变量扩展通常完成。在你的情况，整个的回路及其块读取和所有变量，除了循环变量被扩展为当前值。

The problem with your code snippet is the way variables are expanded. Variable expansion is usually done when a statement is first read. In your case the whole FOR loop and its block is read and all variables, except the loop variables are expanded to their current value.

这意味着％C％在回声%%我，％C％瞬间扩大，所以实际上是作为回声%% I，1 在每次循环迭代。

This means %c% in your echo %%i, %c% expanded instantly and so is actually used as echo %%i, 1 in each loop iteration.

所以，你需要的是延迟变量扩展。找到一些很好的解释一下这里 。

So what you need is the delayed variable expansion. Find some good explanation about it here.

变量，应该是扩大与延迟引用！变量！而不是的％变量％。但是，你需要激活与此功能SETLOCAL ENABLEDELAYEDEXPANSION 和匹配 ENDLOCAL 重置。

Variables that should be delay expanded are referenced with !VARIABLE! instead of %VARIABLE%. But you need to activate this feature with setlocal ENABLEDELAYEDEXPANSION and reset it with a matching endlocal.

您修改code看起来这样的事情：

Your modified code would look something like that:

set TEXT_T="myfile.txt"

set /a c=1

setlocal ENABLEDELAYEDEXPANSION

FOR /F "tokens=1 usebackq" %%i in (%TEXT_T%) do (
  set /a c=c+1

  echo %%i, !c!
)

endlocal

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