Control Flow

Falsy Values

• $false
• $null
• Empty string
• Numeric zeros
• Empty collections implemented IList.
• Single-item collection that contains falsy value, @(0), @($null) for example.

NOTE

You can cast falsy values to boolean.

[bool]@() # False

Newline Indicator

Use ` to indicate a new line if you do want to finish a long command invocation across multiple lines.

gci `
-File `
-Filter '*.mp4'

WARNING

A space is required before the backtick.And no any chacracter is allowed after the backtick.

TIP

Stop using backticks! They're ugly! Use hashtable splatting instead.

$table = @{
 Filter = '*.mp4';
 File = $true
}
gci @table

Multi-Line Piping

Trailing Piper

In multiple piping, we can use trailing | to indicate the new line, PowerShell regconizes these lines as a whole command piping.

gps |
  foreach CPU |
  sort -desc

Leading Piper PowerShell 7+

Starting with PowerShell 7, | is allowed as the first non-space chacracter in a new line.

gps | foreach CPU
  | sort -desc # [!code highlight]

Command Chaining

Multi-Command in Single Line

Use ; to separate commands in the same line. All commands are executed in order.

cd ..; gci -rec -file; echo hello

Chaining And & Or PowerShell 7+

In PowerShell 7, && and || were introduced to do the same command chaining as bash does.

Null-Conditional Operator PowerShell 7+

This feature is basically the same as in C# except a bracing {} is required around variable because ? is valid as part of variable name.

$null.Bar() # exception raised
${null}?.Bar() # ok

$null[0] # exception raised here
${null}?[0] # ok

$null ?? 'I am not null'

$baz ??= 'I am new value'

Ternary Operator PowerShell 7+

No need to explain, same as in C#.

Pattern Matching

Switch statement behaves similarly when the input is a singular object but can enumerate when the input is a collection. It has a few different patterns available:

• Constant: matching by primitive literal.
• Type: matching by target type with -is operator.
• Regex: matching by regex string, specifically for string.
• Wildcard: matching by wildcard string, specifically for string.

Constant Pattern

Type Pattern

Regex Pattern

Wildcard Pattern