PowerShell cmdLet Set-StrictMode

-version / -off

The -version argument takes one of the following four arguments

`1.0`	prohibits references to uninitialized variables, except for uninitialized variables in strings.
`2.0`	`1.0` plus prohibiting references to non-existent properties (members of objects and prohibiting function calls that use the syntax for calling methods.
`3.0`	`2.0` plus prohibiting out of bounds or unresolvable array indexes.
`latest`	Latest version that is available

In order to disable all effects of set-strictMode, it can be set to -off.

Using set-strictMode and param statement

With a few exceptions, the param statement must be the first statement in a PowerShell script. Therefore, the set-strictMode must be placed after the param keyword.

Examples

off

Setting strictMode to -off disables all checks. Undefined variables evaluate to $null without any indication of a (possible) error in the source code.

The following script prints They first said 'hello world', followed by '':

set-strictMode -off

$someText = 'hello world'

write-host "They first said '$someText', followed by '$undefinedText'"

Github repository about-PowerShell, path: /cmdlets/strictMode/set/off.ps1

version 1

set-strictMode -version 1

$val    = 42
$result = $val * $uninitialized_val

Github repository about-PowerShell, path: /cmdlets/strictMode/set/version-1.ps1

This script references an uninitialized variable ($uninitialized_val).

The -version 1 of the set-strictMode statement causes the script to issue the error message The variable '…' cannot be retrieved because it has not been set.

version 2

set-strictMode -version 3

[psCustomObject] $obj = @{ num = 42; txt = 'hello world' }

write-host $obj.num
write-host $obj.unobtainium

Github repository about-PowerShell, path: /cmdlets/strictMode/set/version-2.ps1

This script tries to access a property (member) of an object that does not exist ($obj.unobtainium).

With -version 2, the error message that is thrown is The property '…' cannot be found on this object. Verify that the property exists.

version 3

set-strictMode -version 3

$ary = 'foo', 'bar', 'baz'

write-host $ary[0]
write-host $ary[1]
write-host $ary[2]
write-host $ary[3]

Github repository about-PowerShell, path: /cmdlets/strictMode/set/version-3.ps1

This script creates an array with three elements. When the (inexisting) fourth element is accessed, PowerShell raises the error message Index was outside the bounds of the array.