使用DOS批处理脚本计数在for循环 [英] Counting in a FOR loop using DOS Batch script

问题描述

有人能解释一下吗？我可以用DOS循环来算，使用此方法：

  SET / A XCOUNT = 0
：循环
SET / A XCOUNT + = 1
回声％XCOUNT％
IF％XCOUNT％==4（
  GOTO结束
）ELSE（
  GOTO循环
）
：结束
 

但这种方法不能正常工作（它打印出1文件中的每一行）。它就像变量超出范围：

  SET / A COUNT = 1
FOR / F令牌= *%% A IN（config.properties）DO（
  SET / A COUNT + = 1
  ECHO％COUNT％
）
 

解决方案

它不工作，因为的全部的为环路（含中的命令它）正在评估的时候遇到过，的前的它开始执行。

在换句话说，％计％替换其值 1 之前运行的循环。

您需要的是这样的：

  SETLOCAL ENABLEEXTENSIONS enabledelayedexpansion
SET / A COUNT = 1
FOR / F令牌= *%% A IN（config.properties）DO（
  SET / A COUNT + = 1
  ECHO！算！
）
ENDLOCAL
 

延迟扩展使用！而不是％会给你预期的行为。参见<一个href=\"http://stackoverflow.com/questions/5349153/strange-question-about-windows-batch-file/5349159#5349159\">here.

Can anyone explain this? I am able to count in a loop using DOS, using this method:

SET /A XCOUNT=0
:loop
SET /A XCOUNT+=1
echo %XCOUNT%
IF "%XCOUNT%" == "4" (
  GOTO end
) ELSE (
  GOTO loop
)
:end

But this method does not work (it prints out "1" for each line in the file). It acts like the variable is out of scope:

SET /A COUNT=1
FOR /F "tokens=*" %%A IN (config.properties) DO (
  SET /A COUNT+=1
  ECHO %COUNT%
)

解决方案

It's not working because the entire for loop (including the commands within it) is being evaluated when it's encountered, before it begins executing.

In other words, %count% is replaced with its value 1 before running the loop.

What you need is something like:

setlocal enableextensions enabledelayedexpansion
SET /A COUNT=1
FOR /F "tokens=*" %%A IN (config.properties) DO (
  SET /A COUNT+=1
  ECHO !COUNT!
)
endlocal

Delayed expansion using ! instead of % will give you the expected behaviour. See also here.

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