Powershell if -lt 问题；如果条件为假则返回真 [英] Powershell if -lt problem; returns true if the condition is false

问题描述

我在使用 Powershell 中的小脚本时遇到问题.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 条件仍然计算为 true.

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

推荐答案

Read-Host 总是返回一个 string，-lt 执行词法与作为 LHS 的字符串进行比较:

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'

您必须将从Read-Host返回的字符串转换为数字，以便进行数字比较:

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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