Why is a leading comma required when creating an array?

Question

I want to create an array containing arrays of two numbers. Pretty straightforward. However, If I do not provide a leading comma before the first array, it is incorrect. Why

Answer 1

Powershell uses both a comma and a line break as an array separator. Your first declare:

$files1 = @(
@(4, 1024)
, @((7), (16))
)

Creates the following:

$files1[0] = 4
$files1[1] = 1024
$files1[2] = @(7,16)

Your second declare

$files1 = @(
, @(4, 1024)
, @((7), (16))
)

Creates the following:

$files1[0] = @(4, 1024)
$files1[1] = @(7, 16)

As to the parsing decision, it is dependent on the first non-white space character encountered on a line: Array Literals In PowerShell and Understanding PowerShell Parsing Modes