为什么在使用ENABLEDELAYEDEXPANSION时这个变量不会在for循环中设置？ [英] Why won't this variable set in the for loop while using ENABLEDELAYEDEXPANSION?

问题描述

  @echo off 
 SETLOCAL ENABLEDELAYEDEXPANSION 
 
 set seed = -1 
 echo seed init val：％seed％
 
 for（* .txt）中的%% f（
校验和%% f％种子％
回显错误级别：！ERRORLEVEL！
 set seed =！ERRORLEVEL！
 echo new seed val：！seed！
）
  

输出：

  C：\> returnval 
种子初始值val：-1 
种子在主：FFFFFFFF 
 result.txt的32位校验和是44DD58EE 
错误级别：1155356910 
新种子值：-1 //仍然-1？应该是1155356910 
种子在主：FFFFFFFF 
 test.txt的32位校验和是E245740F 
错误级别：-498764785 
新种子值：-1 
  

设置seed = ERRORLEVEL的行不起作用。

回显ERRORLEVEL使用！否则将无法正常展开和显示。

正如您可以看到当我们获得新的种子值：它仍然是-1

将种子设置为最后一个 ERRORVALUE ？

注意，for循环只是查找我有两个文本文件，并将其送到一个exe返回的文件的校验和，似乎工作正常，因为ERRORLEVEL是exe的结果。）

答案需要在集合上使用/ a，以获取种子获取ERRORLEVEl的数值，然后使用！对于校验和参数种子。

  @echo off 
 SETLOCAL ENABLEDELAYEDEXPANSION 
 
 seed = -1 
 echo seed init val：％seed％
 
 for（* .txt）DO（
 checksum %% f！seed！
回声错误级别：！ERRORLEVEL！
 set / a seed =！ERRORLEVEL！
 echo new seed val：！seed！
）
  pre> 
 
解决方案
您已经知道，您需要使用延迟扩展才能正常工作，因此应该 set seed =！ERRORLEVEL！。和 echo seed值：！seed！时打印出来。经验法则：如果它在一个循环中，那么你必须延迟扩展。
 
@echo off
SETLOCAL ENABLEDELAYEDEXPANSION

set seed=-1
echo seed init val:%seed%

for %%f in (*.txt) DO (
    checksum %%f %seed%
    echo error level: !ERRORLEVEL!
    set seed = !ERRORLEVEL!
    echo new seed val:!seed!
)
Output:
C:\>returnval
seed init val:-1
Seed in main : FFFFFFFF
The 32-bit checksum for result.txt is 44DD58EE
error level: 1155356910
new seed val:-1 //still -1 ?? should be 1155356910
Seed in main : FFFFFFFF
The 32-bit checksum for test.txt is E245740F
error level: -498764785
new seed val:-1
The line that sets seed = ERRORLEVEL does not work.

to echo the ERRORLEVEL I did need to use the "!" otherwise it would not expand and display properly.  

As you can see when we get to new seed value: it is still -1

How do I set seed to the last ERRORVALUE?

(Side note, the for loop is just looking up two text files I have and feeding it to an exe that returns a checksum for the file., that seems to works fine, as the ERRORLEVEL is the result of the exe.)

Answer: needed to use /a on the set to get the seed to take the numeric value of ERRORLEVEl and then use the "!" for the checksum parameter seed as well.
@echo off
SETLOCAL ENABLEDELAYEDEXPANSION

set seed=-1
echo seed init val:%seed%

for %%f in (*.txt) DO (
    checksum %%f !seed!
    echo error level: !ERRORLEVEL!
    set /a seed = !ERRORLEVEL!
    echo new seed val:!seed!
)

解决方案
You already know that you need to use delayed expansion for this to work properly, so it should be set seed = !ERRORLEVEL!. And echo seed value: !seed! when printing it out. The rule of thumb: if it's in a loop, then you have to delay the expansion.

                        
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