Powershell 返回错误结果 [英] Powershell returns wrong result

问题描述

我在 Powershell 中遇到了这个奇怪的问题(不是在其他语言中).任何人都可以向我解释为什么会发生这种情况吗?

我试图返回一个指定的数字(数字 8)，但该函数不断向我抛出所有内容.这是错误还是设计?

函数 GetNum() {返回 10}函数主(){$Number10 = GetNum$number10 #1 为什么这里没有输出???????我不想使用写主机$result = 8 # 我只想要这个数字暂停返回 $result}做 {$again = 主要Write-Host "RESULT IS "$again # 奇怪的结果，我只想要数字 8} while ($again -eq 10) # 由于结果错误，一直循环

解决方案

这是错误还是有意为之?

按设计.在 PowerShell 中，cmdlet 可以返回对象流，就像在 C# 中使用 yield return 返回 IEnumerable 集合一样.

return 关键字不需要返回输出值，它只是退出(或从返回)当前范围.

来自 Get-Help about_Return(强调):

<前>Return 关键字退出函数、脚本或脚本块.有可能用于在特定点退出作用域、返回值或指示已达到范围的末尾.熟悉 C 或 C# 等语言的用户可能希望使用Return 关键字使离开范围的逻辑明确.在 Windows PowerShell 中，每个语句的结果返回为输出，即使没有包含 Return 关键字的语句.C 或 C# 等语言仅返回指定的一个或多个值通过 Return 关键字.

I came across this weird issue in Powershell (not in other languages). Could anyone please explain to me why this happened?

I tried to return a specified number (number 8), but the function keeps throwing everything at me. Is that a bug or by design?

Function GetNum() {
   Return 10
}

Function Main() {

    $Number10 = GetNum
    $number10 #1 WHY NO OUTPUT HERE ??????? I don't want to use write host
    $result = 8  # I WANT THIS NUMBER ONLY
    PAUSE
    return $result
}

do {    
    $again = Main
    Write-Host "RESULT IS "$again # Weird Result, I only want Number 8
} While ($again -eq 10) # As the result is wrong, it loops forever

解决方案

Is that a bug or by design?

By design. In PowerShell, cmdlets can return a stream of objects, much like using yield return in C# to return an IEnumerable collection.

The return keyword is not required for output values to be returned, it simply exits (or returns from) the current scope.

From Get-Help about_Return (emphasis added):

    The Return keyword exits a function, script, or script block. It can be
    used to exit a scope at a specific point, to return a value, or to indicate
    that the end of the scope has been reached.


    Users who are familiar with languages like C or C# might want to use the
    Return keyword to make the logic of leaving a scope explicit.


    In Windows PowerShell, the results of each statement are returned as
    output, even without a statement that contains the Return keyword.
    Languages like C or C# return only the value or values that are specified
    by the Return keyword.

这篇关于Powershell 返回错误结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！