%%F variable always referencing the last item in a FOR loop instead of the current one

问题:

This seems like is should be fairly simple, but I am having trouble getting a FOR loop in DOS to correctly report the current item it is evaluating.

I have a simple DOS batch file that loops through all files in a directory and renames them. Let's say for example my directory contains the following files:

File1.txt File2.txt File3.txt 

I want to remove the TXT extension from each file. So my batch command looks something like:

@echo off

for %%F in ("*.txt") do (   echo %%F   set tmpFile=%%F   echo %tmpFile%   set newFile=%tmpFile:~0,-4%.xml   echo %newFile% ) 

My expected output would be:

File1.txt File1.txt File1.xml File2.txt File2.txt File2.xml File3.txt File3.txt File3.xml 

Instead the output is:

File1.txt File3.txt File3.xml File2.txt File3.txt File3.xml File3.txt File3.txt File3.xml 

It's as if setting %%F to a variable always uses the last file in the collection.

Am I doing something wrong? Please note I know there are better ways to simply change an extension. My finished batch file will perform many more actions, but I can't seem to get past this initial step.

回答1:

It's because you are setting and accessing a variable within a for loop.

You need to use delayed expansion to access them, using !'s instead of %'s.

setlocal enabledelayedexpansion for %%F in ("*.txt") do (   echo %%F   set tmpFile=%%F   echo !tmpFile!   set newFile=!tmpFile:~0,-4!.xml   echo !newFile! ) 

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