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What does the "0" mean in this PHP excerpt?

I am learning from a book called "Head First PHP and MYSQL"

One of the lessons has this line written in it:

$category_totals = array(array($mismatch_categories[0], 0));

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if you have array($variable[0],0)  what does the second zero do?

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Ray PaseurCommented:
$category_totals is assigned to be an array of one element

Inside that array is another array of two elements
    The first element is the zero-th position of the array $mismatch_categories
    The second element is the integer zero

It may be easier to understand if you write it out line-by-line with indenting like this:

$category_totals = array
( array
  ( $mismatch_categories[0]
  , 0

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HTH, ~Ray
also it is much better for me to understand if I do it as it should be done as -
 $insideArray = array($mismatch_categories[0],  0);     // two array elements, , 0 as mismatch and 1 as  0
 echo "Second element is ".$insideArray[1];  // will output "Second element is 0"

//now add to $category_totals
$category_totals = array( $insideArray );

if you want to create an array, you add "Elements" as things you want to get out of array later, arrays are a kind of compartment storage area, each thing between the commas goes into the array as an element |compartment, , data segment| so you can use numbers to get them out later.

you use line of -
$category_totals = array(array($mismatch_categories[0], 0));

is code that works well , but is considered short cut code because it does not create the first array before it creates the second, does all in one line.
Ray PaseurCommented:
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