Problems with multiple arrays forming another array

Problems with multiple arrays forming another array
The following array is formed in the program (the key in the program is dynamic, and here it is written dead)

Array
(
    [Category] = Total
    [January2014_number_stores] = 0
    [February2014_number_stores] = 0
    [March2014_number_stores] = 0
)

And there's an array

Array
(
    [January2014_number_stores] = 155
    [February2014_number_stores] = 155
    [March2014_number_stores] = 155
)
Array
(
    [January2014_number_stores] = 126
    [February2014_number_stores] = 126
    [March2014_number_stores] = 126
)
Array
(
    [January2014_number_stores] = 37
    [February2014_number_stores] = 37
    [March2014_number_stores] = 37
)
Array
(
    [January2014_number_stores] = 9
    [February2014_number_stores] = 9
    [March2014_number_stores] = 9
)
Array
(
    [January2014_number_stores] = 4
    [February2014_number_stores] = 4
    [March2014_number_stores] = 4
)

Now you want to assign the sum of the same key value in the array in the second set to the first array, how do I write it? How do I write if the key value is dynamic and regular?
------Solution--------------------

$a = Array (
' Category ' = ' total ',
' January2014_number_stores ' = 0,
' February2014_number_stores ' = 0,
' March2014_number_stores ' = 0,
);

$b = Array (
Array
' January2014_number_stores ' = 155,
' February2014_number_stores ' = 155,
' March2014_number_stores ' = 155,
),
Array
' January2014_number_stores ' = 126,
' February2014_number_stores ' = 126,
' March2014_number_stores ' = 126,
),
Array
' January2014_number_stores ' = 37,
' February2014_number_stores ' = 37,
' March2014_number_stores ' = 37,
),
Array
' January2014_number_stores ' = 9,
' February2014_number_stores ' = 9,
' March2014_number_stores ' = 9,
),
Array
' January2014_number_stores ' = 4,
' February2014_number_stores ' = 4,
' March2014_number_stores ' = 4,
),
);
foreach ($b as $r) {
foreach ($r as $k = = $v) {
if (! isset ($a [$k])) $a [$k] = 0;
$a [$k] + = $v;
}
}
Print_r ($a);

Array
(
[Category] = Total
[January2014_number_stores] = 331
[February2014_number_stores] = 331
[March2014_number_stores] = 331
)

