PowerShell无控制台程序弹出数组计数弹窗，如何消除？

问题原因 #

[System.Collections.ArrayList]的Add()方法会返回元素添加后的索引值（即当前数组的大小），在无控制台模式编译运行时，这个返回值未被处理，被当作输出触发了额外窗口显示该数值。

解决方案 #

只需丢弃Add()方法的返回值，避免产生输出即可，以下是三种常用实现方式：

方式1：使用[void]前缀 #

修改verifyProcessEnd函数内的添加逻辑：

if($finishedList -notcontains($name)){
    [void]$finishedList.Add($name) 
}

方式2：将结果赋值给$null #

if($finishedList -notcontains($name)){
    $null = $finishedList.Add($name) 
}

方式3：通过管道输出到Out-Null #

if($finishedList -notcontains($name)){
    $finishedList.Add($name) | Out-Null
}

修改后的完整脚本 #

#verify that all processes have ended
function verifyProcessEnd{
    DO{   
        foreach($name in $processList){
            if((Get-Process $name -ErrorAction SilentlyContinue) -eq $null){
            #fill our finished processes list
                if($finishedList -notcontains($name)){
                    [void]$finishedList.Add($name) 
                }
            }
        }
    }while($finishedList.Count -ne $processList.Count)
}

#____________________________________ Main ____________________________________#
#get the list of processes to check for - these must match the service name (minus extension) in task manager
[System.Collections.ArrayList]$processList =  'WINWORD', 'msedge' #can be changed to any processes
# create a new list for finished processes. 
[System.Collections.ArrayList]$finishedList = @()
$wshell = New-Object -ComObject Wscript.Shell
$wshell.Popup("Please wait for all processes to end before starting the program", 10, "Done",0x1)
verifyProcessEnd
$wshell.Popup("All startup processes have completed. It is safe to start the program", 10, "Done",0x1)

内容的提问来源于stack exchange，提问作者AngelOfChaos