Powershell中字符串内的Concat变量

Question

我正在尝试在字符串中连接变量。

代码：

$uniqueID = "123"
$Key = '<add key="uniqueID" value="$uniqueID" />'
write-host $Key

结果我想要：

<add key="uniqueID" value="123" />

结果我得到：

<add key="uniqueID" value="$uniqueID" />

Answer 1

尝试这个 -

$Key = "<add key=`"uniqueID`" value=`"$($uniqueID)`" />"

要么

$Key = "<add key=`"uniqueID`" value=`"$uniqueID`" />"

若要强制Windows PowerShell从字面上解释双引号，请使用反引号字符。这样可以防止Windows PowerShell将引号解释为字符串定界符。

信息-

如果您看一下Get-Help about_Quoting_Rules，它会说：

SINGLE AND DOUBLE-QUOTED STRINGS
   When you enclose a string in double quotation marks (a double-quoted
   string), variable names that are preceded by a dollar sign ($) are
   replaced with the variable's value before the string is passed to the
   command for processing.

   For example:

       $i = 5
       "The value of $i is $i."

   The output of this command is:
       The value of 5 is 5.

   Also, in a double-quoted string, expressions are evaluated, and the
   result is inserted in the string. For example:

       "The value of $(2+3) is 5."

   The output of this command is:

       The value of 5 is 5.

   When you enclose a string in single-quotation marks (a single-quoted
   string), the string is passed to the command exactly as you type it.
   No substitution is performed. For example:

       $i = 5
       'The value of $i is $i.'

   The output of this command is:

       The value $i is $i.

   Similarly, expressions in single-quoted strings are not evaluated. They
   are interpreted as literals. For example:

       'The value of $(2+3) is 5.'

   The output of this command is:

       The value of $(2+3) is 5.

您的代码未评估值的原因是因为您使用单引号将变量包装起来$key。用双引号将其包装，然后使用子表达式运算符（$($UniqueID）和反引号可以解决问题，或者仅使用$UniqueIDwill也足够。