Powershell 替换字符串中的字符 [英] Powershell Replace Characters in a String

问题描述

使用 powershell，但对其他潜在解决方案持开放态度....

Using powershell, but open to other potential solutions....

我有一个很长的字符串.我需要用掩码字符(句点或空格)替换该字符串中位置的几个字符序列.我不知道这些角色会是什么，但我知道他们需要是别的东西.我已经使用 mid 编写了代码，并使用 mid 和位置数字遍历字符串，但这有点麻烦，想知道是否有更快/更优雅的方法.

I have a long string. I need to replace several sequences of characters by position in that string with a mask character (period or space). I don't know what those characters are going to be, but I know they need to be something else. I have written code using mid and iterating through the string using mid and position numbers, but that is a bit cumbersome and wondering if there is a faster/more elegant method.

示例:鉴于 2 个字符串:

Example: Given the 2 strings:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
12345678901234567890123456

我想替换字符 2-4, 8-9, 16-22, &23 与 .，产生:

I want to replace characters 2-4, 8-9, 16-22, & 23 with ., yielding:

A...EFGH..KLMNOP.....VWX.Z
1...5678..123456.....234.6

我可以用一系列 MID 来做到这一点，但我只是想知道是否有某种更快的屏蔽功能来实现这一点.我必须通过数百万行和第二次计数来做到这一点.

I can do that with a series of MID's, but I was just wanting to know if there were some sort of faster masking function to make this happen. I have to do this through millions of rows and second count.

推荐答案

试试这个:

$regex = [regex]'(.).{3}(.{4}).{2}(.{6}).{5}(.{3}).(.+)'
$replace = '$1...$2..$3.....$4.$5'

('ABCDEFGHIJKLMNOPQRSTUVWXYZ',
 '12345678901234567890123456') -Replace $regex,$replace

A...EFGH..KLMNOP.....VWX.Z
1...5678..123456.....234.6

-replace 操作符单次操作比 string.replace() 慢，但优点是可以对字符串数组进行操作，比 string 方法加 foreach 循环要快.

The -replace operator is slower than string.replace() for a single operation, but has the advantage of being able to operate on an array of strings, which is faster than the string method plus a foreach loop.

这是一个示例实现(需要 V4):

Here's a sample implementation (requires V4):

$regex =  [regex]'(.).{3}(.{4}).{2}(.{6}).{5}(.{3}).(.+)'
$replace = '$1...$2..$3.....$4.$5'

filter fix-file {
 $_ -replace $regex,$replace | 
 add-content "c:\mynewfiles\$($file.name)"
}

get-childitem c:\myfiles\*.txt -PipelineVariable file |
 get-content -ReadCount 1000 | fix-file 

如果你想使用掩码方法，你可以从中生成 $regex 和 $replace :

If you want to use the mask method, you can generate $regex and $replace from that:

$mask  = '-...----..------.....---.-'

 $regex = [regex]($mask -replace '(-+)','($1)').replace('-','.')

 $replace = 
 ([char[]]($mask -replace '-+','-') |
  foreach {$i=1}{if ($_ -eq '.'){$_} else {'$'+$i++}} {}) -join ''

$regex.ToString()
$replace

(.)...(....)..(......).....(...).(.)
$1...$2..$3.....$4.$5

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