Powershell：如何删除数组控制台输出中的第一个空行？

Question

我有一些代码（tio.run），输出到控制台：

$exeoutput = @(
    "     Compression          : CCITT Group 4",
    "     Width                : 3180",
    "     Height               : 4908"
)
$var = $exeoutput.trim() | Select-String "Height|Width|Compress"
echo ----------------
$var
echo ---------------

输出是

----------------

Compression          : CCITT Group 4
Width                : 3180
Height               : 4908
----------------

如何从控制台输出中删除上 ---------------- 之后的第一个空行？

Answer 1

$var 变量的每个元素都是 MatchInfo 类型。您需要将它们转换为 string，如下所示：

[string[]]$var

或

$var.foreach([string])

阅读ForEach and Where magic methods:

ForEach(type convertToType)

Unique to the ForEach method, you can pass a type into the ForEach method if you want to convert every item in a collection into another type. For example, imagine you have a collection of objects and you want to convert those objects into their string equivalent. Here is what that would look like with the ForEach method:
# Get a collection of processes
$processes = Get-Process
# Convert the objects in that collection into their string equivalent
$processes.foreach([string])
You could have performed the same task by typecasting the collection into an array of type string (e.g. [string[]]$processes), and typecasting the array is in fact significantly faster, however there’s a very good chance you wouldn’t even notice the difference in execution time unless you were working with a very, very large collection. Despite the time difference, I will tend to prefer the ForEach method syntax in certain situations if it allows me to maintain elegance in the implementation by avoiding extra round brackets in the scripts I write.

示例代码片段（针对进行了更新）：

$var = $exeoutput.trim() | Select-String "Height|Width|Compress"
'-' * 15
$var.foreach([string])
'-' * 15

结果：

---------------
Compression          : CCITT Group 4
Width                : 3180
Height               : 4908
---------------

请注意 echo 是 Write-Output cmdlet 的别名：

This cmdlet is typically used in scripts to display strings and other objects on the console. However, because the default behavior is to display the objects at the end of a pipeline, it is generally not necessary to use the cmdlet.

请注意 you can multiply numbers, strings, and arrays（请参阅 ˙'-' * 15˙ 而不是 ----------------）。

Powershell：如何删除数组控制台输出中的第一个空行？

Powershell: How to remove first empty blank line in console output of an array?

powershell

blank-line

ForEach(type convertToType)