Multiple Variable Conditions for If Statement in PowerShell

Question

Thanks for the help in this, I think i have over complicated the below but the logic just isn't responding how my mind is telling it too.

Logic in Question:

$a = "One"
$b = "Two"
$c = "Three"
$d = "Four"

If( {$a -and $b} -ne {$c and $d} ) {
   Write-Host "Values are Different"
} Else {
   Write-Host "values are the same"
}

I want the If statement to run when $a and $b are different to $c and $d, If the are the same see below, I want it to output that the values are the same

$a = "One"
$b = "One"
$c = "One"
$d = "One"

Thanks in advance!

Answer 1

You can use Compare-Object to compare the value pairs as arrays :

if (Compare-Object $a, $b   $c, $d  -SyncWindow 0) {
  'different'
} else {
  'same'
}

Note that this is convenient, but relatively slow, which may matter in a loop with many iterations.

• The Compare-Object cmdlet compares two arrays and by default returns information about their differences.

• -SyncWindow 0 compares only directly corresponding array elements; in other words: $a must equal $c , and $b must equal $d ; without -SyncWindow , the array elements would be compared in any order so that 1, 2 would be considered equal to 2, 1 for instance.

• Using the Compare-Object call's result as a conditional implicitly coerces the result to a Boolean, and any nonempty result - indicating the presence of at least 1 difference - will evaluate to $True .

---

As for what you tried :

Use of { ... } in your conditional is not appropriate.
Expressions enclosed in { ... } are script blocks - pieces of code you can execute later, such as with & or .

Even if you used (...) instead to clarify operator precedence ( -ne has higher precedence than
-and ), your conditional wouldn't work as expected, however:

• ($a -and $b) -ne ($c -and $d) treats all variables as Booleans ; in effect, given PowerShell's implicit to-Boolean conversion, you're comparing whether one value pair has at least one empty string to whether the other doesn't.

Answer 2

In addition to the answer from mklement0 and avoiding the rather slow Compare-Object cmdlet :

In what you tried , you will need to compare one specific value with each of the rest of the vales:

($a -eq $b) -and ($a -eq $c) -and ($a -eq $d)

Because the Comparison Operators ( -eq ) take a higher precedence than the Logical Operators ( -and ), you can leave the brackets and simplify it to:

$a -eq $b -and $a -eq $c -and $a -eq $d

To make this more DRY and easily expandable for even more values:

if (!($a, $b, $c | Where {$_ -ne $d})) {
  'different'
} else {
  'same'
}

Answer 3

Just remove these {} brackets from the if statement

   $a = "One"
    $b = "One"
    $c = "One"
    $d = "One"

    If($a -and $b -ne $c -and $d) {
       Write-Host "Values are Different"
    } Else {
       Write-Host "values are the same"
    }