Checking if a string is NULL or EMPTY is very common requirement in Powershell script. If we don’t do that we will end up with run time errors if we try to perform some operation on that string variable which i
string to System.Management.Automation.ScriptBlock Cannot use Set-Acl properly despite being file owner and being a member of Administrators Group. Cannot validate argument on parameter 'Name'. The argument is null or empty. Provide an argument that is not null or empty, and then try the ...
PS>$value=$nullPS>Write-Output"'The value is$value'"'The value is ' 这是我喜欢在日志消息中使用变量时将括号放在变量周围的原因之一。 当值位于字符串末尾时,标识变量值的边缘更为重要。 PowerShell PS>$value=$nullPS>Write-Output"The value is [$value]"The value is [] ...
function Test-MrParameterValidation { [CmdletBinding()] param ( [ValidateNotNullOrEmpty()] [string[]]$ComputerName = $env:COMPUTERNAME ) Write-Output $ComputerName } 详细输出 如果要编写复杂的代码,则内联注释非常有用,但除非用户查看代码,否则不会看到它们。 以下示例中的函数在 foreach 循环内有一...
[string]$ComputerNmae) Write-Output$ComputerNmae} 如果需要参数有多个值,指定类型为string[] functionTest-MrParameterValidation { [CmdletBinding()]param( [Parameter(Mandatory)] [string[]]$ComputerName) Write-Output$ComputerName} 如果需要指定一个默认参数需要将ValidateNotNullOrEmpty参数验证属性与默认值一起...
param( [Parameter(Mandatory)] [ValidateNotNullOrEmpty()] [string[]]$UserName ) ValidateNotNullOrWhiteSpace 验证属性ValidateNotNullOrWhiteSpace 属性指定分配的值不能为以下任何值:$null 空字符串 ("") 空数组 @() 仅包含空格字符的字符串,如制表符、空格、回车符和换行符 包含空或仅包含...
不希望支持用户交互的主机应该返回null。 string output = ((CustomPSHostUserInterface)host.UI).Output; return output; } //定义承载MSH运行空间的应用程序提供的属性和功能 //System.Management.Automation.Runspaces到Msh运行时的公共接口。提供用于创建管道、访问会话状态等的api。 //GUID数据类型是表示类标识符(...
Optionally, you can provide a brief help string that describes the default value of your parameter, by adding thePSDefaultValueattribute to the description of your parameter, and specifying theHelpproperty ofPSDefaultValue. To provide a help string that describes the default value (100) of theSize...
[string]$todaysDate='1/10/2020'$todaysDate??= (Get-Date).ToShortDateString()$todaysDate Output 1/10/2020 Null-conditional operators?.and?[] Note This feature was moved from experimental to mainstream in PowerShell 7.1. A null-conditional operator applies a member access,?., or element...
publicstringf(stringx){returnx;} Callingf(null)returnsnull. Why does it matter that$nullis unconditionally converted to[string]::Empty? All other collection-type parameters of a function can take three different empty-ish values: a collection object containing no items (eg.@(),@{},[System....