MAX in PHP returning wrong value - php

Question

I have an array with key and value pair. I'm building this array dynamically and below is the code.
$x[] = array('type_name' => $value->name,
'percentage'=> intval($percentage));
My intention is to get the maximum value and for that I do
max($x);
However it is returning the wrong value actually the lowest value. Following is my array. Any help would be awesome.
$x = array(
array(
'type_name' => 'type 1'
'percentage' => 10,
),
array(
'type_name' => 'type 2'
'percentage' => 15,
),
array(
'type_name' => 'type 3'
'percentage' => 45,
),
);
Thanks is advance.

Answer 1

From php max() documentation :
// Multiple arrays of the same length are compared from left to right
It means that if you want to compare "percentage" values first instead of "type_name" values, you'll have to change their order in the array.
So, you could build your array like this ("percentage" comes first) and it should work :
$x[] = array(
'percentage'=> intval($percentage),
'type_name' => $value->name
);
For example :
$x = array(
array(
'percentage' => 10,
'type_name' => 'type 1'
),
array(
'percentage' => 15,
'type_name' => 'type 2'
),
array(
'percentage' => 45,
'type_name' => 'type 3'
),
array(
'percentage' => 25,
'type_name' => 'type 4'
)
);
print_r(max($x));
Output :
Array
(
[percentage] => 45
[type_name] => type 3
)
Hope it helps.

Answer 2

You need to read how the max compares against different types of data. In your case, you are trying to compare against one of the array item i.e. percentage inside one of the item so the function max does not know to do this.
There is an example by Revo in the manual which shows you how to do this.

Answer 3

You are creating an array of arrays. max doesn’t know that your arrays should be compared by the 'percentage' key, so it can’t be used here.
Instead, find the maximum value yourself. For example, like this:
$maxPercentage = false;
foreach ($x as $item) {
if ($maxPercentage === false || $item['percentage'] > $maxPercentage) {
$maxPercentage = $item['percentage'];
}
}
Now, $maxPercentage will store maximum percentage. Of, if you want an item with maximum percentage, get it like this:
$maxPercentage = false;
$maxItem = false;
foreach ($x as $item) {
if ($maxPercentage === false || $item['percentage'] > $maxPercentage) {
$maxPercentage = $item['percentage'];
$maxItem = $item;
}
}