问题
In powerShell you compare a boolean with a string with the "-eq" operator it will always return the same boolean as I used to compare.
E.g.
$shouldBeFalse = $true -eq "hello"
$shouldBeTrue = $false -eq "hello"
The variable $shouldBeFalse is $true. The variable $shouldBeTrue is $false.
I had to use the "Equals" method:
$shouldBeFalse = $true.Equals("hello")
In this case $shouldBeFalse is $false.
But why returns the -eq operator with boolean these kind of results?
回答1:
PowerShell will always evaluate using the type of the left-side argument. Since you have a boolean on the left PowerShell will try and cast "Hello" as a boolean for the purpose of evaluating with -eq.
So in your case "hello" is converted to a boolean value [bool]"hello" which would evaluate to True since it is not a zero length string. You would see similar behavior if you did the opposite.
PS C:\> "hello" -eq $true
False
PS C:\> [bool]"hello" -eq $true
True
In the first case $true is converted to a string "true" which does not equal "hello" hence false. In the second case we cast "hello" to boolean so the -eq will compare boolean values. For reasons mentioned about this evaluates to True.
Another good explanation comes from this answer which might get your question flagged as a duplicate: Why is $false -eq "" true?
来源：https://stackoverflow.com/questions/26545686/why-does-true-eq-string-returns-true