PowerShell: while statement

Assignment

It is possible to assign a value to a variable in the while loop's condition. After assigning a value to the variable, the value of the variable is checked in a boolean context.

This is demonstrated in the following example:

$nums  = 42, 99, 17, 0, 12

$index = -1
function nextNum() {
   $script:index ++
   return $script:nums[$script:index]
}

while ($num = nextNum) {
   write-host "num = $num"
}

Github repository about-powershell, path: /language/statement/while/assignment.ps1

Because 0 is considered to be $false in a boolean context, the loop terminates when nextNum() returns 0. Thus, this script prints

num = 42
num = 99
num = 17

It is also possible to assign a value and check the assigned value with a comparison operator. Because the assignment has a lower precedence than the comparison operator, the assignment must be put into parentheses:

$nums  = 42, 99, 17, 0, 12

$index = -1
function nextNum() {
   $script:index ++
   return $script:nums[$script:index]
}

while ( ($num = nextNum) -gt 22) {
   write-host "num = $num"
}

Github repository about-powershell, path: /language/statement/while/assignment-gt.ps1

This script prints

num = 42
num = 99

PowerShell: while statement

Assignment

See also