如何在批处理文件中的for循环中执行可变长度的子字符串? [英] How to do substring with variable length in a for loop inside batch files?

问题描述

我正在尝试在批处理文件中进行一些字符串比较和提取.该操作在SVN信息库中的一组文件夹名称上进行.

I am trying to do some string comparison and extraction in a batch file. The operation takes place on a set of folder names from a SVN repository.

for /f %%f in ('svn list https://dev_server/svn/product/branches') do ( 
    set folder=%%f 

    echo Folder: %folder%

    :: get substring from %folder% starting at 0 with a length of %length%
    :: if this substring is equal to %folderStart% then get substring from %folder% starting at position %length%   
)

这里有两个问题:

1. 由于某些原因，未将%% f的值分配给％folder％.
2. 即使我已经在网络上进行了广泛的搜索，我也没有找到解决长度可变的子字符串的解决方案.批处理文件子字符串函数:〜似乎只采用固定的整数值.

有人知道我如何实现上面代码中注释部分中的功能吗?

Does anyone have an idea how I could implement the functions in the commented section in the code above?

推荐答案

动态子字符串易于扩展，易于扩展.

Dynamic substring is easy with delayed expansion.

setlocal enableDelayedExpansion
set "string=1234567890"

::using a normal variable
set len=5
echo !string:~0,%len%!

::using a FOR variable
for /l %%n in (1 1 10) do echo !string:~0,%%n!

它还可以用于搜索和替换

It can also work with search and replace

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