PHP 7+
As of PHP 7, this can be done concisely using usort with an anonymous function that uses the spaceship operator to compare elements.
You can do an ascending sort like this:
usort[$inventory, function [$item1, $item2] {
return $item1['price'] $item2['price'];
}];
Or a descending sort like this:
usort[$inventory, function [$item1, $item2] {
return $item2['price'] $item1['price'];
}];
To understand how this works, note that usort takes a user-provided comparison function that must behave as follows [from the docs]:
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
And note also that , the spaceship operator,
returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater
which is exactly what usort needs. In fact, almost the entire justification given for adding to the language in //wiki.php.net/rfc/combined-comparison-operator is that it
makes writing ordering callbacks for use with
usort[]easier
PHP 5.3+
PHP 5.3 introduced anonymous functions, but doesn't yet have the spaceship operator. We can still use usort to sort our array, but it's a little more verbose and harder to understand:
usort[$inventory, function [$item1, $item2] {
if [$item1['price'] == $item2['price']] return 0;
return $item1['price'] < $item2['price'] ? -1 : 1;
}];
Note that although it's fairly common for comparators dealing with integer values to just return the difference of the values, like $item2['price'] - $item1['price'], we can't safely do that in this case. This is because the prices are floating point numbers in the question
asker's example, but the comparison function we pass to usort has to return integers for usort to work properly:
Returning non-integer values from the comparison function, such as float, will result in an internal cast to integer of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.
This is an important trap to bear in mind when using
usort in PHP 5.x! My original version of this answer made this mistake and yet I accrued ten upvotes over thousands of views apparently without anybody noticing the serious bug. The ease with which lackwits like me can screw up comparator functions is precisely the reason that the easier-to-use spaceship operator was added to the language in PHP 7.
Each entry in the associative array is characterized by a unique key-value pair. An array can contain singular data types belonging to variables or other arrays as its elements. There are multiple ways to sort an array of associative arrays by the value of a specified key.
Approach 1: Using the array_multisort[] method
The array_multisort[] method is used to return a sorted array. String keys will be maintained, but the numeric keys are re-indexed, and they start at 0 and increase by 1. This function can sort multiple arrays at once or a multidimensional array.
array_multisort[array, sort_order, sort_type];
Example: In this approach, initially an array of associative arrays is defined. Then, a new array is created in order to store the keys as the attribute of the main array upon which we wish to sort. The array_multisort[] method is then applied to this created array and the desired sort type. In case two or more keys are the same, the values appear in the order of storage.
PHP
Output:
Modified Array : Array
[
[0] => Array
[
[Name] => AMAN
[marks] => 55
]
[1] => Array
[
[Name] => ANjali
[marks] => 98
]
[2] => Array
[
[Name] => ASHIKA
[marks] => 67
]
[3] => Array
[
[Name] => BASHIKA
[marks] => 87
]
[4] => Array
[
[Name] => YASHIKA
[marks] => 22
]
[5] => Array
[
[Name] => YASHIKA
[marks] => 100
]
[6] => Array
[
[Name] => YASHITA
[marks] => 24
]
]Explanation: The main array is sorted based on names in ascending order.
Approach 2: Using the usort[] method
This method sorts the given array using a user-defined comparison function. The user-defined function should return an integer than 0 if the first argument is than the second argument. This method assigns new keys to the elements in the array. It just removes any existing keys that may have been assigned, rather than just simply reordering the keys.
usort[array, user_def_func]
Example:
PHP
Output: The DescSort[] method sorts the marks in descending order.
Modified Array : Array
[
[0] => Array
[
[Name] => YASHIKA
[marks] => 100
]
[1] => Array
[
[Name] => ANjali
[marks] => 98
]
[2] => Array
[
[Name] => BASHIKA
[marks] => 87
]
[3] => Array
[
[Name] => ASHIKA
[marks] => 67
]
[4] => Array
[
[Name] => AMAN
[marks] => 55
]
[5] => Array
[
[Name] => YASHITA
[marks] => 24
]
[6] => Array
[
[Name] => YASHIKA
[marks] => 22
]
]