powershell - PowerShell：条件“if”语句的奇怪行为

Question

看看下面的代码。如果我只用第一个“if”语句运行它，我会得到想要的结果。添加第二个“if”语句（如下所示），我没有得到想要的结果。这里有什么问题以及为什么 PowerShell 以两种不同的方式表现！

$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：将条件语句格式化为单行，以便于上面阅读和解释。

Answer 1

这是预期的行为。我认为您可能误解了控制流程的进展方式。

$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")

也许您的意思是使用elseif语句？

$CACHE_OS = ""
$OPERATINGSYSTEM = "WIN832_9200"

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

Answer 2

它按预期工作。在第一个 IF 中，$OPERATINGSYSTEM 匹配“WIN832”，因此 $CACHE_OS 设置为“WIN832”，正如您所料，ELSE 语句列表未执行。

在第二个 IF 中，$OPERATINGSYSTEM 不匹配“WIN832”，因此跳过了 IF 语句列表并开始执行 ELSE 部分，并为 $CACHE_OS 分配了 $OPERATINGSYSTEM 的值，即“WIN832_9200”。