PowerShell中负数索引生成子串的办法

DAIC

本篇文章引用的小例子来自如下链接:
http://bbs.chinaunix.net/thread-957849-1-1.html

Bash 裡有變量擴展 ${var:offset:length} ${var:offset}

[victor@localhost ~]$ echo ${USER} victor [victor@localhost ~]$ echo ${USER:1} ictor [victor@localhost ~]$ echo ${USER:5:1} r [victor@localhost ~]$ echo ${USER:(-1)} r [victor@localhost ~]$ echo ${USER:(-2)} or [victor@localhost ~]$ echo ${USER:(-5)} ictor

如何使用PowerShell完成呢??

PS C:\> "victor" victor PS C:\> "victor".SubString(1); ictor PS C:\> "victor".SubString(5,1); r

对于使用负数做索引, .Net Framework的System.String中几个实例方法都不支持. 只好先用slices获取负数索引, 然后用System.String提供的静态方法Join连接起来.

PS C:\> [string]::join('', ('victor')[-5..-1]) ictor PS C:\> [string]::join('', ('victor')[-2..-1]) or PS C:\> [string]::join('', ('victor')[-1..-1]) r

当然这几个例子比较简单, 有时间我还会添加更多的例子.

http://blog.chinaunix.net/uid-9781829-id-1997697.html

PowerShell

1. PS C:\Users\admin> "powershellabc1234"[-1..-5] -join ""
   
2. 4321c
   
3. PS C:\Users\admin>

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