powershell - 奇怪的字符串生成器

Question

我在函数内部有 StringBuilder 对象。有字符串型返回前还有一些系统对象 后。

function test
{
    $strArr = @("aaa", "bbb", "ccc")
    $stringBuilder = New-Object System.Text.StringBuilder
    foreach ($item in $strArr)
    {
        $stringBuilder.AppendLine($item)            
    }
    $out = $stringBuilder.ToString()
    write-host "FIRST OUT: ", $out, "OUTTYPE:", $out.GetType()
    return $out
}

$out2 = test
Write-Host "-------------------"
write-host "SECOND OUT2: ", $out2, "OUT2TYPE:", $out2.GetType()

输出:

FIRST OUT:  aaa
bbb
ccc
 OUTTYPE: System.String -> THAT'S OK
-------------------
SECOND OUT2 (ALL ARE four times - WHY???):  aaa
bbb
ccc
 aaa
bbb
ccc
 aaa
bbb
ccc 
 aaa
bbb
ccc
 OUT2TYPE: System.Object[] -> Object?????

为什么都是四次？为什么对象不是字符串？

Answer 1

试试这个:

function test

    {
    $strArr = @("aaa", "bbb", "ccc")
    $stringBuilder = New-Object System.Text.StringBuilder
    foreach ($item in $strArr)
    {
        $stringBuilder.AppendLine($item) | Out-Null           
    }
    $out = $stringBuilder.ToString()
    write-host "FIRST OUT: ", $out, "OUTTYPE:", $out.GetType()
    return $out
}

$out2 = test
Write-Host "-------------------"
write-host "SECOND OUT2: ", $out2, "OUT2TYPE:", $out2.GetType()

解释是 $stringBuilder.AppendLine()输出一些东西，它被添加到函数的输出中。

编辑:
函数输出的一切都被认为是函数的返回。换句话说，在PowerShell中，函数的返回值不仅仅是 return之后的值。 keywork ($out) 而是函数内部输出的所有数据(以数组形式)。看着 about_Return我们看到

In Windows PowerShell, the results of each statement are returned as output, even without a statement that contains the Return keyword.