The If Statement
SHORT DESCRIPTION
A language command for running a command block or blocks based on the results of one or more conditional tests
LONG DESCRIPTION
You can use the if statement to run a code blocks if a specified conditional test evaluates to true. You can also specify one or more additional conditional tests to run if all prior tests evaluate to false. Finally, you can specify an additional code block that is run if no other prior conditional test evaluates to true.
The following shows the if statement syntax:
if (<test1>)
{<code_block1>}
[elseif (<test2)
{<code_block2>}]
[else
<code_block3>}]
When you run an if statement, the Windows PowerShell evaluates the <test1> conditional expression true or false. If <test1> is true, then <code_block1> runs and PowerShell exits the if statement. If <test1> is false, PowerShell evaluates the condition specified by <test2>. If <test2> is true, then <code_block2> runs and PowerShell exits the if statement. If both <test1> and <test2> evaluate to false, then <code_block3> runs and PowerShell exits the if statement.
You can use multiple elseif statements to chain a series of conditional tests, each of which is examined only if all the previous tests are false. Note, if you need to create an if statement containing many elseif statements within it, consider using a switch statement instead.
The simplest if statement contains a single command in the code block and does not contain any elseif statements or an else statement. The following shows the simplest form of the if statement:
if ($a -gt 2)
{
Write-Host "The value $a is greater than 2"
}
In this example, if $a is greater than 2, the condition evaluates to true and the code block runs. However, if $a is less than or equal to 2 or is not an existing variable, the if statement does not display any message. By adding an else statement, you can be sure to display a message when $a is less than or equal to 2, as the next example shows:
if ($a -gt 2)
{
Write-Host "The value $a is greater than 2"
}
else
{
Write-Host "The value $a is less than or equal to 2, is not created or is not initialized."
}
To further improve on this example, you can use the elseif statement to display a message when the value of $a is equal to 2, as the next example shows:
if ($a -gt 2)
{
Write-Host "The value $a is greater than 2"
}
elseif ($a -eq 2)
{
Write-Host "The value $a is equal to 2"
}
else
{
Write-Host "The value $a is less than 2 or is not created or initialized."
}
SEE ALSO
For information about using comparison operators, enter the following command at the PowerShell command prompt:
For information about the switch statement, enter the following command at the PowerShell command prompt:
help about_switch