if($value-eq$null) {'The array is $null'}if($value-ne$null) {'The array is not $null'} 如果我未定义$value,则第一个的计算结果为$true,消息为The array is $null。 这里的陷阱是,可以创建一个允许二者都为$false的$value PowerShell $value= @($null)
Now you might get a question, what if the $mystring has white space as value. It is neither a EMPTY value nor a NULL value so we can not use IsNullOrEmpty() method in this case. If you try it, it will return False which means string is not NULL or EMPTY. In such cases we can...
The argument is null or empty. Provide an argument that is not null or empty, and then try the command again. CannotConnect,PSSessionStateBroken Cant access a fileshare through a remote PS Session Cant make work with variable in Get-ADuser command to get UPN Cant return string for msExch...
function Test-MrParameterValidation { [CmdletBinding()] param ( [ValidateNotNullOrEmpty()] [string[]]$ComputerName = $env:COMPUTERNAME ) Write-Output $ComputerName } 详细输出 如果要编写复杂的代码,则内联注释非常有用,但除非用户查看代码,否则不会看到它们。 以下示例中的函数在 foreach 循环内有一...
Assign a string value to a variable. $str="Have a nice day."[string]::IsNullOrWhiteSpace($str) Output: False Use the$nullVariable to Check if a String Variable Is Not Null or Empty in PowerShell $nullis one of the automatic variables in PowerShell, which represents NULL. You can use ...
特性的值HelpMessage不应为空字符串或 null 值,因为这会导致 PowerShell 解释器在执行函数或 cmdlet 时引发错误。 方式 指定HelpMessage属性的值。 示例 错 PowerShell FunctionBadFuncEmptyHelpMessageEmpty {Param( [Parameter(HelpMessage='')] [String]$Param)$Param}FunctionBadFuncEmptyHelpMessage...
The value is: 1 The value is: 2 The value is: 4 If you want a function that can take pipeline input or input from a parameter, then theprocessblock needs to handle both cases. For example: PowerShell functionGet-SumOfNumbers{param( [int[]]$Numbers)begin{$retValue=0}process{if($nul...
Indicates if this PowerShell object is the owner of the runspace or RunspacePool assigned to this object. Runspace Sets an associated Runspace for this PowerShell instance. This can be null in which case a new runspace is created whenever Invoke* method is called. RunspacePool Sets an assoc...
Value is the property value to search for. Enclose text values and variables in single quotation marks ('Value'or'$Variable'). If a variable value contains single quotation marks, you need to identify (escape) the single quotation marks to expand the variable correctly. For example, instead ...
If you simply remove the[string]type then it will work as expected: function f2 { param ( $x ) return $x } $null -eq (f2 -x $null) There is no value in declaring a parameter as type string because all classes in .Net have to derive from theObjectclass. Therefore every class impl...