代码之家 › 专栏 › 技术社区 › Vippy

PowerShell:条件“if”语句的异常行为

conditional-statements behavior match powershell

1

Vippy · 技术社区 · 14 年前

看看下面的代码。如果我只运行第一个“If”语句,我会得到所需的结果。加上第二个“如果”语句(如下所示),我没有得到所需的结果。这里出了什么问题,为什么PowerShell以两种不同的方式运行!

$CACHE_OS = ""
$OPERATINGSYSTEM = "WIN832_9200"

if ( $OPERATINGSYSTEM -match "WIN832" ) { $CACHE_OS = "WIN832" } else { $CACHE_OS = $OPERATINGSYSTEM }
if ( $OPERATINGSYSTEM -match "WIN864" ) { $CACHE_OS = "WIN864" } else { $CACHE_OS = $OPERATINGSYSTEM }

$CACHE_OS

仅供参考:为了更容易阅读和解释,将条件语句格式化为一行。

2 回复 | 直到 14 年前

1

4

latkin 14 年前

这是预期的行为。我认为你可能误解了控制流程的进展。

$CACHE_OS = ""
$OPERATINGSYSTEM = "WIN832_9200"

if ( $OPERATINGSYSTEM -match "WIN832" )  # true
{
  $CACHE_OS = "WIN832"  # $cache_os set to "WIN832"
}
else
{
  $CACHE_OS = $OPERATINGSYSTEM
}

# at this point $cache_os has a value of "WIN832"

if ( $OPERATINGSYSTEM -match "WIN864" ) # false
{
  $CACHE_OS = "WIN864"
}
else # control goes here
{
  $CACHE_OS = $OPERATINGSYSTEM   # $cache_os is re-assigned, new value is "WIN832_9200"
}

$CACHE_OS  # output the current value ("WIN832_9200")

也许你的意思是用 elseif 陈述

$CACHE_OS = ""
$OPERATINGSYSTEM = "WIN832_9200"

if ( $OPERATINGSYSTEM -match "WIN832" )
{
  $CACHE_OS = "WIN832"
}
elseif ( $OPERATINGSYSTEM -match "WIN864")
{
  $CACHE_OS = "WIN864"
}
else
{
  $CACHE_OS = $OPERATINGSYSTEM
}

2

0

Shay Levy 14 年前

它正在按预期工作。在第一个IF中,$OPERATINGSYSTEM匹配“WIN832”,因此$CACHE_OS被设置为“WIN832”,正如您所期望的, ELSE语句列表不执行 。

在第二个IF中,$OPERATINGSYSTEM与“WIN832”不匹配,因此跳过IF语句列表 ELSE部分开始 中,并且$CACHE_OS被分配了$OPERATINGSYSTEM的值,即“WIN832_9200”。