Powershell if -lt问题；如果条件为假，则返回true

问题描述

我对Powershell中的小脚本有疑问.这是我的脚本:

I have a problem with small script in Powershell.Here is my script:

$number = Read-Host "Enter a number"
if ($number -lt 3){
    Write-Host "Number is too low."
    break
}

但是，例如，当我输入25时，if条件仍然为true.

But when I enter 25, for example, the if conditional still evaluates to true.

推荐答案

Read-Host始终返回 string ，而-lt对字符串进行 lexical 比较为LHS:

Read-Host always returns a string, and -lt performs lexical comparison with a string as the LHS:

PS> '25' -lt 3
True  # because '2' comes lexically before '3'

为了执行数字比较，必须将从Read-Host返回的字符串转换为 number :

You must convert the string returned from Read-Host to a number in order to perform numerical comparison:

[int] $number = Read-Host "Enter a number"
if ($number -lt 3){
    Write-Host "Number is too low."
    break
}

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